TCL Commands

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Tcl CommandsQuick Reference

Surya Gadde


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Table of Contents

Simple Text output (puts command) ........................................................................................................ 6

Assigning values to variables (set command) ........................................................................................... 6

Evaluations and Substitutions ................................................................................................................... 6

Using (Quotes) ................................................................................................................................. 6

Using {} (braces) .................................................................................................................................... 7

Using [ ] (Brackets) ................................................................................................................................ 7

Math functions .......................................................................................................................................... 8

Switch command ....................................................................................................................................... 9

If command ............................................................................................................................................. 10

A simple if command ........................................................................................................................ 10

If..else command ................................................................................................................................. 10

If elseif.else command................................................................................................................... 10

While Loop .............................................................................................................................................. 10

For loop ................................................................................................................................................... 11

Procedures .............................................................................................................................................. 11

Global ...................................................................................................................................................... 12

Upvar ....................................................................................................................................................... 13

List ........................................................................................................................................................... 15

lindex ................................................................................................................................................... 15

llength ................................................................................................................................................. 15

lappend ............................................................................................................................................... 16

linsert .................................................................................................................................................. 16

lreplace ................................................................................................................................................ 16

lsearch ................................................................................................................................................. 17

lsort ..................................................................................................................................................... 17

lrange .................................................................................................................................................. 18

concat .................................................................................................................................................. 18

String command ...................................................................................................................................... 19

string length ........................................................................................................................................ 19


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string index .......................................................................................................................................... 19

string range ......................................................................................................................................... 19

string compare .................................................................................................................................... 19

string first ............................................................................................................................................ 20

string last ............................................................................................................................................. 20

string wordstart .................................................................................................................................. 21

string wordend .................................................................................................................................... 21

string match ........................................................................................................................................ 21

string tolower ...................................................................................................................................... 22

string toupper ..................................................................................................................................... 22

string totitle ........................................................................................................................................ 22

string trim ............................................................................................................................................ 22

string trimleft ...................................................................................................................................... 22

string trimright .................................................................................................................................... 23

format ..................................................................................................................................................... 23

regexp ..................................................................................................................................................... 24

regsub ..................................................................................................................................................... 25

Array ........................................................................................................................................................ 25

array exists .......................................................................................................................................... 25

array names ........................................................................................................................................ 26

array size ............................................................................................................................................. 26

array get .............................................................................................................................................. 26

array set .............................................................................................................................................. 26

array startsearch ................................................................................................................................. 27

array nextelement ............................................................................................................................... 27

array anymore ..................................................................................................................................... 28

array donesearch ................................................................................................................................ 28

Accessing Files ......................................................................................................................................... 29

Open .................................................................................................................................................... 29

Close .................................................................................................................................................... 29

Gets ..................................................................................................................................................... 29

Puts ..................................................................................................................................................... 30


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Read .................................................................................................................................................... 30

Seek ..................................................................................................................................................... 30

tell ....................................................................................................................................................... 31

flush ..................................................................................................................................................... 31

eof ....................................................................................................................................................... 31

Glob ......................................................................................................................................................... 33

File status ................................................................................................................................................ 34

file size................................................................................................................................................. 34

file atime ............................................................................................................................................. 34

file mtime ............................................................................................................................................ 34

file exists ............................................................................................................................................. 34

File isdirectory ..................................................................................................................................... 35

file isfile ............................................................................................................................................... 35

file owned ........................................................................................................................................... 35

file executable ..................................................................................................................................... 35

file readable ........................................................................................................................................ 36

file writable ......................................................................................................................................... 36

file type ............................................................................................................................................... 36

File lstat ............................................................................................................................................... 37

file stat ................................................................................................................................................ 37

File System .............................................................................................................................................. 38

file readlink ......................................................................................................................................... 38

file copy ............................................................................................................................................... 38

file rename .......................................................................................................................................... 38

file delete ............................................................................................................................................ 39

file mkdir ............................................................................................................................................. 39

File and Path Names ............................................................................................................................... 39

file dirname ......................................................................................................................................... 39

file extension ....................................................................................................................................... 40

file rootname ...................................................................................................................................... 40

file tail ................................................................................................................................................. 40

file nativename ................................................................................................................................... 40


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file normalize ...................................................................................................................................... 41

file split ................................................................................................................................................ 41

file attributes ....................................................................................................................................... 41

file link ................................................................................................................................................. 42

file pathtype ........................................................................................................................................ 42

file separator ....................................................................................................................................... 43

file system ........................................................................................................................................... 43

file volumes ......................................................................................................................................... 43

Exec ......................................................................................................................................................... 43

Info Commands ....................................................................................................................................... 44

info args............................................................................................................................................... 44

info body ............................................................................................................................................. 44

info cmdcount ..................................................................................................................................... 44

info commands ................................................................................................................................... 45

info exists ............................................................................................................................................ 45

info globals .......................................................................................................................................... 46

info hostname ..................................................................................................................................... 46

info library ........................................................................................................................................... 46

info nameofexecutable ....................................................................................................................... 46

info patchlevel..................................................................................................................................... 47

info procs ............................................................................................................................................ 47

info script ............................................................................................................................................ 47

info sharedlibextension....................................................................................................................... 47

info tclversion ..................................................................................................................................... 47

info vars ............................................................................................................................................... 47

Source command .................................................................................................................................... 48

Package Commands ................................................................................................................................ 48

package provide .................................................................................................................................. 49

pkg_mkIndex ....................................................................................................................................... 49

package require .................................................................................................................................. 49

Eval Command ........................................................................................................................................ 50


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Simple Text output (puts command)

% puts "Hello World - In quotes"

Hello World - In quotes

%

% puts {Hello World - In Braces}

Hello World - In Braces

Assigning values to variables (set command)

Set command used to set variables.

% set X "This is a string"

This is a string

%

% set Y 1.24

%

%puts $X

This is a string

%

%puts $Y

1.24

%

%puts The string is : $X

The string is : This is a string

Unset command used to unset/remove a variable

% set x 5

5% puts $x

5

% unset x

%puts $x

can't read "x": no such variable ---- variable

%

Evaluations and Substitutions

Using (Quotes)

In Tcl, the evaluation of a command is done in two phases; a substitution phase and a commandevaluation phase.

Backslash Sequence

string output hex value

\a ............. Audible alert (Bell) .............................\x07

\b ............. Backspace .......................................... \x08

\f .............. Form Feed (Clear screen) ....... \x0c


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\n ............. New Line ............................................\x0a

\r .............. Carriage Return ................................. \x0d

\t .............. Tab ..................................................... \x09

\v ............. Vertical Tab ........................................ \x0b

\ddd ......... Octal value ......................................... d = 0-7

\xhh ......... Hex value ............................................ h = 0-9,A-F,a-f

% set a 10

10

%

% puts "a value is : $a"

a value is : 10

%

% puts "a value is : \$a" -------- A back slash removes the meaning of the following character

a value is : $a

%

Using {} (braces)

% set name "BillGates"BillGates

%

% puts {My name is $name} ---- No substitution happens with in the braces

My name is $name

%

% puts "My name is $name" ----Substitution happens with in the quotes

My name is BillGates

%

% puts {"My name is $name"} ----Observe the quotes with in braces

"My name is $name"

%

% puts "{My name is $name}" ----Observe the braces with in quotes

{My name is BillGates}

%

Using [ ] (Brackets)

% set y [set x "def"]

def

%

% puts "X value is : $x"

X value is : def

%% puts "Y value is : $y"

Y value is : def

%


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Math functionsTcl supports the following mathematical functions in expressions.

abs acos asin atan

atan2 bool ceil cos

cosh double entier exp

floor fmod hypot int

isqrt log log10 max

min pow rand round

sin sinh sqrt srand

tan tanh wide

OPERATORS

The valid operators are listed below, grouped in decreasing order of precedence:

- + ~ !

Unary minus, unary plus, bit-wise NOT, logical NOT. None of these operators may be applied to string

operands, and bit-wise NOT may be applied only to integers.

* / %

Multiply, divide, remainder. None of these operators may be applied to string operands, and remainder

may be applied only to integers. The remainder will always have the same sign as the divisor and an

absolute value smaller than the divisor.

+ -

Add and subtract. Valid for any numeric operands.

>

Left and right shift. Valid for integer operands only.

&

Bit-wise AND. Valid for integer operands only.

^

Bit-wise exclusive OR. Valid for integer operands only.

|

Bit-wise OR. Valid for integer operands only.

&&Logical AND. Produces a 1 result if both operands are non-zero, 0 otherwise. Valid for numeric operands

only (integers or floating-point).

||

Logical OR. Produces a 0 result if both operands are zero, 1 otherwise. Valid for numeric operands only

(integers or floating-point).

x?y:z


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If-then-else, as in C. If x evaluates to non-zero, then the result is the value of y. Otherwise the result is

the value of z. The x operand must have a numeric value.

% set x 10

10

% set y 15

15

%

% expr $x + $y

25

%

% expr $x * $y

150

%

% expr pow(3,2)

9.0

%

% expr floor(2.345)2.0

%

% expr ceil(2.999)

3.0

%

Switch command

switch string pattern1 body1 ?pattern2 body2?...?patternN bodyN? ?default?

If no match found it goes to default.

Note: args, patterns or parameters which are mentioned in ?? are the optional.

% set x 10

10

%

% switch $x 10 { puts "X value is : $x" }

X value is : 10

%switch $x {

"10" { puts "X is : $x " }

default { puts "No match found" }

}

X is : 10%

% switch $x {

abc { puts "abc found" }

default { puts "No match found" }

}

No match found


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If command

Syntax : if expr1 ?then? body1 elseif expr2 ?then? body2 elseif ... ?else? ?bodyN?

A simple if command

% if { $x == 10 } {

puts "X values is : 10"}

X values is : 10

%

If..else command

% if { $x == 15 } {

puts "X values is : 15"

} else {

puts "X values is not equals to 15"

}

X values is not equals to 10

%

If elseif.else command

% if { $x < 10 } {

puts "X value is lessthan 10"

} elseif { $x > 10 } {

puts "X value is greater then 10"

} else {

puts "X value is equals to 10"

}

X value is equals to 10

%

While Loop

% set x 1;

1

%

% while {$x < 5} {

puts "x is $x";

incr x; ---------- incr command used to increment a variable(Default increment value 1.

}

x is 1

x is 2

x is 3

x is 4

%


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For loop

Synatax : for start test next body

% for { set i 0} {$i


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Global

%set x 5

5

%puts "X value is: $x"

X values is: 5%

%proc test { } {

puts " X value in side proc is: $x

}

%

%test

can't read "x": no such variable -----proc test is not aware of variable x defined outside the procedure

while executing

"puts "X value is:$x""

(procedure "test" line 2)

invoked from within

"test"

%

% proc test { } {

global x; -------------------- Declaring 'x' as global variable

incr x;

puts "X value in side proc is: $x"

}

%

% test

X value in side proc is: 6

%

% puts "Now X value is: $x"Now X value is: 6

%

%


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Upvar

Syntax : upvar ?level? otherVar1 myVar1 ?otherVar2 myVar2 ...?

Example #1

% proc SetPositive {variable value } {

upvar $variable myvar;if {$value < 0} { set myvar [expr -$value];} else {set myvar $value;} -- Converting a variabel to +ve value

puts "........ $variable $value myvar : $myvar....."

return $myvar;

}

%

%

% SetPositive x 5;

% SetPositive y -5;

%

%puts "X : $x Y: $y\n"

X : 5 Y: 5

%

% proc two {k} {

upvar 1 $k z ; --------- Giving reference of 'z' in proc one(i.e one level up), to 'z' in this proc.

Now this 'z' gets the value of 'z' in proc one i.e. 5

upvar 2 x a; --------- Giving reference of 'x' in global space(i.e two levels up), to 'a' in this proc.

Now a gets the value of 'x' i.e. 5

puts "two: Z: $z A: $a";

set z 1; ---------------- Finally this will refer the value 'y' in global space.

set a 2; ---------------- Finally this will refer the value 'x' in global space.

}%

% proc one {y} {

upvar $y z; ------ Giving reference of 'y' in global space, to z.

Now 'z' gets the value of 'y' i.e. 5

puts "one: Z: $z";

two z;

}

%

% one y;

one: Z: 5

two: Z: 5 A: 5%

% puts "\nX: $x Y: $y"

X: 2 Y: 1

%

%


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Example #2

% set x 10;

% set y 15;

%

% proc test { } {

upvar y z;

puts "---- z refers \'y\' value : $z ----"

set z 20; ---------------- This will reflect in 'y' value

test2

}

%

% test

---- z refers 'y' value : 15 ----

%

% puts "Now y became : $y"

Now y became : 20

%

%% proc test2 { } {

upvar 2 x k;

puts "---- k refers \'x\' value : $k ----"

set k 5; --------------- This will reflect in 'x' value

}

%

% test2

---- k refers 'x' value: 10 ----

%

% puts "Now x became : $x"

Now x became : 5%

%


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List

Syntax :

list ?arg1 arg2 ...?

set lst {{item 1} {item 2} {item 3}}

set lst [split "item 1.item 2.item 3" "."] ------> split string ?splitChars?

Splits the string into a list of items at splitChars.

set lst [list "item 1" "item 2" "item 3"]

%set lst [list "item 1" "item 2" "item 3"]

{item 1} {item 2} {item 3}

%

%puts "List values are : $lst"List values are : {item 1} {item 2} {item 3}

%

%

% set lst [split "24/01/1985" "/"]

24 01 1985

%

%

% puts "List values are : $lst"

List values are : 24 01 1985

%

%

lindex

Syntax: lindex list index ----- Index values starts from '0'

% set lst " 1 2 3 4 5 6 7 8"

1 2 3 4 5 6 7 8

%

% puts "[lindex $lst 3]"

4

%

%

llength

Syntax; llength list

%

% puts [llength $lst]

8

%


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lappend

Syntax: lappend listName ?arg1 arg2 ... argn?

% lappend lst 9 10

%

%puts "$lst"1 2 3 4 5 6 7 8 9 10 ------------- 9 and 10 appended at the end of the list 'lst'

%

%

linsert

Syntax : linsert list index arg1 ?arg2 ... argn?

% puts "[linsert $lst 3 44]"

1 2 3 44 4 5 6 7 8 9 10 ----------- Inserted '44' at index '3' i.e. as a fourth value in the list.

%

%% set newlst [linsert $lst 3 44]

%

% puts "New list : $newlst"

New list : 1 2 3 44 4 5 6 7 8 9 10

%

% puts "Old list lst is : $lst"

Old list lst is : 1 2 3 4 5 6 7 8 9 10 ------ No change in the original list

%

lreplace

Syntax : lreplace list first last ?arg1 ... argn?

% set newlst [lreplace $lst 2 5 3456] ----- It replaces the 2 to 5 index values with the given numer

%

% puts " New list : $newlst"

New list : 1 2 3456 7 8 9 10

%

%

% puts " Old list : $lst"

Old list : 1 2 3 4 5 6 7 8 9 10

%

%


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lsearch

Syntax: lsearch list pattern

% set lst "1 2 3 4 5 6 7 8 9 10"

% puts "Value '5' is found at index value: [lsearch $lst 5]" ---- returns the index value of the pattern in

the list, if pattern foundValue '5' is found at index value: 4

%

%

By default, lsearch uses the globbing method of finding a match. Globbing is the wildcarding technique

that the shell uses.

globbing wildcards are:

* --- Matches any quantity of any character

? --- Matches one occurrence of any character

\X --- The backslash escapes a special character in globbing just the way it does in Tcl substitutions.

Using the backslash lets you use glob to match a * or ?.

[...] --- Matches one occurrence of any character within the brackets. A range of characters can be

matched by using a range between the brackets. For example, [a-z] will match any lower case

letter.

% set list "{Washington 1789} {Adams 1797} {Jefferson 1801} {Madison 1809} {Monroe 1817} {Adams

1825}"

%% puts "Jefferson is found at index : [lsearch $list Jefferson*]"

Jefferson is found at index : 2

%

% puts "Madison is found at index : [lsearch $list *diso*]"

Madison is found at index : 3

%

%

lsort

Syntax : lsort -option list

Options are,

-dictionary : Dictionary order (2 comes before 10, a comes before B, etc)

-decreasing : Largest items first

% set lst " 5 3 1 2 02 001 10 7 6 4 9 8"

%

% puts [lsort $lst]

001 02 1 10 2 3 4 5 6 7 8 9


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%

% puts [lsort -decreasing $lst]

9 8 7 6 5 4 3 2 10 1 02 001

%

% puts [lsort -dictionary $lst]

1 001 2 02 3 4 5 6 7 8 9 10

%

lrange

Syntax : lrange list first last

% set lst "1 2 3 4 5 6 7 8 9 10"

%

% puts [lrange $lst 3 7]

4 5 6 7 8

%

%

concat

Syntax: concat ?arg1 arg2 ... argn?

% set list1 "1 2 3 4 5"

1 2 3 4 5

%

% set list2 "a b c d e"

a b c d e

%

%

% set list3 [concat $list1 $list2]

1 2 3 4 5 a b c d e

%

%

% puts "Now list3 is : $list3"

Now list3 is : 1 2 3 4 5 a b c d e

%

%


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String command

string length

Syntax: string length string

Returns the length of string

% set string "this is my test string"

%

% puts "Length of the string is : [string length $string]"

Length of the string is : 22

%

%

string index

Syntax: string index string index

Returns the char at the given index position in string.

% set string "My Name Is Surya"

%

% puts "[string index $string 3] is the second character in \"$string\""

N is the second character in "My Name Is Surya"

%

%

string range

Syntax: string range string first last

Returns a string composed of the characters from first to last

% set string "this is my test string"

%

% puts "\"[string range $string 5 10]\" are characters between the 5'th and 10'th"

"is my " are characters between the 5'th and 10'th

%

%

string compare

Syntax: string compare string1 string2

Compares string1 to string2 and returns

* -1 ..... If string1 is less than string2

* 0 ........ If string1 is equal to string2

* 1 ........ If string1 is greater than string2 These comparisons are done lexicographically,

not numerically.


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% set string1 "Surya"

%

% set string2 "Gadde"

%

% puts [string compare $string1 $string2]

1 ----------------- string1 is greater than string2

%

% set string1 " Hello World "

%

% set string2 " This is test message "

%


-1 ----------------- string1 is less than string2

% set string1 " Hello"

%% set string2 " Hello"

%


0 ----------------- string1 is equlas to string2

%

string first

Syntax: string first string1 string2 ?startIndex?

Searches for string1 in string2 and returns the index value in string2 if string found. Otherwise returns

-1.

% puts [string first "this" "hello world, this is test message"]

13 --------- String 'this' found at index 13 in the second string

%

% puts [string first "is" "my name is surya, this is test message"]

8 --------- 'is' found at 8th position in the second string

%

% puts [string first "is" "my name is surya, this is test message" 10]

20 --------- 'is' found at 20th position after index value '10'

%

string last

Syntax: string last string1 string2 ?startIndex?

Searches for string1 in string2 from the last. Returns index value if string1 found in string2. Other wise

returns -1.


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% puts [string last "is" "my name is surya, this is test message" ]

23 --------------- 'is' found at 8th, 20th and 23 rd positions. But it returns last match.

%

% puts [string last "is" "my name is surya, this is test message" 20]

8 --------------- it starts searching for 'is' from index value '20' to the start index.

%

string wordstart

Syntax: string wordstart string index

Searches for the starting of word after the given indexvalue.

% puts [string wordstart "hello world test message" 0]

0 ----- It searches for the word 'tcl' towards start of the sting from the given index '0' and the word

found at 0'th position and returned '0'

%

% puts [string wordstart "hello world test message" 8]6 ----- It searches for the nearest word before index '8' and found a word started at index '6'

%

% puts [string wordstart "hello world test message" 20]

17 ----- Before index '20', a word started at index '17'

%

string wordend

Syntax: string wordend string index

Searches for the word end after the given index value.

% puts [string wordend "hello world test message" 0]

5 ----- After starting from the given index '0' a word end found at '5'th index.

%

% puts [string wordend "hello world test message" 12]

16 ----- After starting from the given index '12'th pisition, a word end found at 16th position.

%

string match

Syntax: string match ?-nocase? pattern string

% puts [string match "*ampl*" "this is sample message"]1 --- found pattern "*ampl* at "sample"

%


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string tolower

Syntax: string tolower string ------ Convert a string/word to lower case

% puts [string tolower "HELLO WORLD"]

hello world

string toupper

Syntax: string toupper string ------ Convert a string/word to upper case

% puts [string tolower " hello world "]

HELLO WORLD

%

string totitle

Syntax: string totitle string ------ Convert first letter of the stirng/word to Upper case

% puts [string totitle " hello world "]

Hello world

string trim

Syntax: string trim string ?trimChars?

trimChars removed from both ends. By default trimChars are whitespace (spaces, tabs, newlines)

% puts [string trim " hello world "]

hello world

%

% puts [string trim "hi ---- hello world----- hi" hi]

---- hello world-----

%

string trimleft

Syntax: string trimleft string ?trimChars?

trimChars removed from the left. By default trimChars are whitespace (spaces, tabs, newlines)

% puts [string trimleft " hello world " ]

hello world

%

% puts [string trimleft "hello world" he]

llo world


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string trimright

Syntax: string trimtrim string ?trimChars?

trimChars removed from the right. By default trimChars are whitespace (spaces, tabs, newlines)

%puts [string trimright " hello world " ]hello world

%

% puts [string trimright "hello world" rld]

hello wo

format

Syntax: format formatString ?arg1 arg2 ... argN?

set labels [format "%-20s %+10s " "Item" "Cost"]

set price1 [format "%-20s %10d Cents Each" "Tomatoes" "30"]set price2 [format "%-20s %10d Cents Each" "Peppers" "20"]

set price3 [format "%-20s %10d Cents Each" "Onions" "10"]

set price4 [format "%-20s %10.2f per Lb." "Steak" "3.59997"]

puts "\n Example of format:\n"

puts "$labels"

puts "$price1"

puts "$price2"

puts "$price3"

puts "$price4"

Output:

Example of format:

Item Cost

Tomatoes 30 Cents Each

Peppers 20 Cents Each

Onions 10 Cents Each

Steak 3.60 per Lb.


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regexp

Syntax: regexp ?switches? exp string ?matchVar? ?subMatch1 ... subMatchN?

Searches string for the regular expression exp.

Regular expressions can be expressed in just a few rules.

^ ----- Matches the beginning of a string

$ ----- Matches the end of a string

. ----- Matches any single character

* ----- Matches any count (0-n) of the previous character

+ ----- Matches any count, but at least 1 of the previous character

[...] ----- Matches any character of a set of characters

[^...] ----- Matches any character *NOT* a member of the set of characters following the ^.

(...) ----- Groups a set of characters into a subSpec.

Example :

set sample "Where there is a will, There is a way."

set result [regexp {[a-z]+} $sample match]

puts "Result: $result match: $match"

set result [regexp {([A-Za-z]+) +([a-z]+)} $sample match sub1 sub2 ]

puts "Result: $result Match: $match 1: $sub1 2: $sub2"

Output:

Result: 1 match: here

Result: 1 Match: Where there 1: Where 2: there

[0-9]+ or \d+ matches any numeric string.

[a-z]+ matches any lowercase word

[A-Z]+ matches any uppercase words

\s+ matches any number of spaces

[a-zA-z0-9] matches any alpha-numberic word with any case


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regsub

Syntax: regsub ?switches? exp string subSpec varName

Searches string for substrings that match the regular expression exp and replaces them with subSpec.

set sample "Where there is a will, There is a way."regsub "way" $sample "lawsuit" sample2

puts "New: $sample2"

Output:

New: Where there is a will, There is a lawsuit.

Array

We can define arrays in three types.

1) array set array1 [list {123} {Abigail Aardvark} {234} {Bob Baboon} {345} {Cathy Coyote}]

2) array set array1 { {123} {Abigail Aardvark} {234} {Bob Baboon} {345} {Cathy Coyote} }

3) set array1(123) "Abigail Aardvark"

set array1(234) "Bob Baboon"

set array1(345) "Cathy Coyote"

% puts $array1(234)Bob Baboon

%

array exists

Syntax: array exists arrayName

Returns 1 if arrayName is an array variable. Returns 0 if arrayName is a scalar variable, proc, or does not

exist.

% if {[array exist array1]} {

puts "array1 is an array"

} else {

puts "array1 is not an array"

}

array1 is an array

%


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array names

Syntax: array names arrayName ?pattern

Returns a list of the indices for the associative array arrayName. If pattern is supplied, only those indices

that match pattern are returned.

% puts "Array1 has the following entries: \n [array names array1] \n"

345 234 123

array size

Syntax: array size arrayName

Returns the number of elements in array arrayName.

%puts "Size of the array1 is: [array size array1]"

3

%

array get

Syntax: array get arrayName

% puts [array get array1]

345 {Cathy Coyote} 234 {Bob Baboon} 123 {Abigail Aardvark}

%

array set

Syntax: array set arrayName dataList

Converts a list into an associative array.

% puts [array set array1 {456 "hello World"}]

%

% puts "Size of the array1 is: [array size array1]"

4

% puts [array get array1]

345 {Cathy Coyote} 234 {Bob Baboon} 123 {Abigail Aardvark} 456 {hello World}


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There are two methods for iterating through the contents of an associative array.

Using a foreach loop with the output from the array names command Using the array startsearch commands

Method#1

% foreach id [array names array1] {

puts "$array1($id) has ID: $id"

}

Cathy Coyote has ID: 345

Bob Baboon has ID: 234

Abigail Aardvark has ID: 123

hello world has ID: 456

Method #2

array startsearch

Syntax: array startsearch arrayName

Initializes arrayName for use with the iterating commands, and returns the searchID token that must be

passed to those commands.

% puts [array startsearch array1]

s-1-array1 ------- searchID

%

array nextelementSyntax: array nextelement arrayName searchID

Returns the index of the next element in arrayName. If there are no more elements in arrayName, then

an empty string is returned.


s-1-array1

% puts [array nextelement array1 s-1-array1]

345


234% puts [array nextelement array1 s-1-array1]

123


456

% puts [array nextelement array1 s-1-array1] ----- no elements in array to show

%


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array anymore

Syantax: array anymore arrayName searchID

Returns a 1 if there are still elements in arrayName to be returned by nextelement. Otherwise, it returns

0.


s-1-array1

%

% puts [array anymore array1 s-1-array1]

1


345


1


234

% puts [array anymore array1 s-1-array1]1


123


1


456


0 --------- There are no elements in the array

array donesearch

Syntax: array donesearch arrayName searchID

Destroys the state information associated with the iteration commands. This command should be

executed when an iteration is complete.


s-1-array1

%


1

% puts [array donesearch array1 s-1-array1]

%


--------

couldn't find search "s-1-array1" ------ searchID got destroyed

while executing

"array anymore array1 s-1-array1"


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Accessing Files

Tcl supports an interface to the file system using the buffered i/o mechanism.

Open

Syntax: open fileName ?access? ?permission?

Opens a file and returns a token to be used when accessing the file.

* FileName is the name of the file to open.

* access is the file access mode

= r ......Open the file for reading. The file must already exist.

= r+ ...Open the file for reading and writing. The file must already exist.

= w.....Open the file for writing. Create the file if it doesn't exist, or set the length to zero if

it does exist.

= w+..Open the file for reading and writing. Create the file if it doesn't exist, or set thelength to zero if it does exist.

= a......Open the file for writing. The file must already exist. Set the current location to the

end of the file.

= a+...Open the file for writing. If the file does not exist, create it. Set the current location

to the end of the file.

* permission is an integer to use to set the file access permissions. The default is rw-rw-rw-

(0666).

CloseSyntax: close fileID

Closes a file previously opened with open, and flushes any remaining output.

Gets

Synatx: gets fileID ?varName?

Reads a line of input from FileID.

If there is a varName argument, gets returns the number of characters read (or -1 if an EOF occurs), andplaces the line of input in varName.


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Puts

Synatx: puts ?-nonewline? ?fileID? string

Writes the characters in string to the stream referenced by fileID(writes at the end).

FileID is one of:* The value returned by a previous call to open with write access.

* stdout

* stderr

Read

Syntax#1 read ?-nonewline? fileID

Reads all the remaining bytes from fileID, and returns that string. If -nonewline is set, then the last

character will be discarded if it is a newline. Any existing end of file condition is cleared before the read

command is executed.

Syntax#2 read fileID numBytes

Reads up to numBytes from fileID, and returns the input as a Tcl string. Any existing end of file condition

is cleared before the read command is executed.

Seek

Syntax: seek fileID offset ?origin?

Change the current position within the file referenced by fileID. Note that if the file was opened with

"a" access that the current position can not be set before the end of the file for writing, but can be set to

the beginning of the file for reading.

* fileID is one of:

= a File identifier returned by open

= stdin

= stdout

= stderr

* offset is the offset in bytes at which the current position is to be set. The position from which

the offset is measured defaults to the start of the file, but can be from the current location, or the end

by setting origin appropriately.

* origin is the position to measure offset from. It defaults to the start of the file. Origin must be

one of:

= start.........Offset is measured from the start of the file.

= current...Offset is measured from the current position in the file.

= end...........Offset is measured from the end of the file.


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tell

Syntax: tell fileID

Returns the position of the access pointer in fileID as a decimal string.

flush

Syntax: flush fileID

Flushes any output that has been buffered for fileID.

eof

Syntax: eof fileID

returns 1 if an End Of File condition exists, otherwise returns 0.

Examples:

% cat myfile

This is line1

This is line2

This is line3

This is line4

%% open myfile r

file5

%

% gets file5 ------- gets reads only one line

This is line1

%

% gets file5

This is line2

%

% read file5 ------- read reads remaining

This is line3This is line4

%

%

% read file5 ----- nothing to read

%

% close file5 ----- closing the previously opened file


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% cat myfile

This is line1

This is line2

This is line3

This is line4

%

% open myfile r

file5

%

% read file5 10 ----- reads only 10bytes

This is li

%

% gets file5 ------ get the current position to end of the line

ne1

%

% gets file5

This is line2

%% seek file5 0 start ---- seek the position to the 0th byte from the start of the file

% gets file5

This is line1

%

% seek file5 5 start --- seek the position to the 5th byte from the start ofthe file

% gets file5 ------ gets the current position to the end of the line

is line1

%

% tell file5 ---- returns the position number

14

%% close file5

%

% open myfile w --- Opens file for writing

file5

%

% puts file5 "This is new line adding to the file" --- writing a line

% puts file5 "This is another line adding to the file" --- writing another line

%

% close file5

%

% cat myfile ----- overwritten the file

This is new line adding to the file

This is another line adding to the file

%


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% cat myfile

This is line1

This is line2

This is line3

This is line4

%

%

%

% open myfile a ----- Opening a file for appedning

file5

%

% puts file5 "This appends at the end of the file"

% close file5

%

%

% cat myfile

This is line1

This is line2This is line3

This is line4

This appends at the end of the file ---- New line appended at the end

%

%

Glob

Syntax: glob ?switches? pattern ?pattern?

returns a list of file names that match pattern

Switches may be one of:

-nocomplain ---- Allows glob to return an empty list without causing an error. Without this flag, an

error would be generated when the empty list was returned.

-- ----- This is default

Pattern follows the same matching rules as the string match globbing rule

% glob /root/myfile ----- Returned the file

/root/myfile

%

% glob /root/myfile1 ----- Thrown an error as the file doesnt exists

no files matched glob pattern "/root/myfile1"

%

% glob -nocomplain /root/myfile1 ------- Doesnt thrown any error even the file was not exists

%


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File status

file size

Syntax: file size name

Returns the size of name in bytes.

%% file size myfile

92

%

file atime

Syntax: file atime name

Returns the number of seconds since 1/1/1970 when the file name was last accessed. Generates an

error if the file doesn't exist.

% file atime myfile

1335162779

%

file mtime

Syntax: file mtime name

Returns the time of the last data modification in seconds since Jan 1, 1970.

% file mtime myfile

1335162776

%

file exists

Syntax: file exists name

Returns a 1 if the file name exists, and the user has search access in all the directories leading to the file.

Otherwise, a 0 is returned.

% file exists myfile

1

%

% file exists nofile

0

%


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File isdirectory

Syntax : file isdirectory name

Returns 1 if file name is a directory, otherwise returns 0.

% mkdir mydir

%

%file isdirectory mydir1

%

% file isdirectory not-a-dir

0

file isfile

Syntax: file isfile name

Returns 1 if file name is a regular file, otherwise returns 0.

% touch newfile

%

% file isfile newfile1

% file isfile nofile

0

%

file owned

Syntax: file owned name

Returns 1 if the file is owned by the current user, otherwise returns 0.

% file owned myfile

1

%% file owned /home/testuser/testfile

0

%

file executable

Syntax: file executable name

Returns a 1 if file has execute permissions to the current user, otherwise returns a 0.

% ls -l myfile

-rw-r--r-- 1 root root 92 Apr 23 12:02 myfile

%

% file executable myfile

0% chmod 755 myfile

%

% ls -l myfile

-rwxr-xr-x 1 root root 92 Apr 23 12:02 myfile

%

% file executable myfile

1


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file readable

Syntax: file readable name

Returns 1 if it has read permissions to the current user, otherwise returns 0.

% ls -l myfile

-rw-r--r-- 1 root root 92 Apr 23 12:02 myfile%

% file readable myfile

1

%

file writable

Syntax: file writable name

Returns 1 if file has write permissions to the current user, otherwise returns 0.

% file writable myfile

1%

file type

Syntax: file type name

Returns a string giving the type of file name, which will be one of:

* file...................................Normal file

* directory........................Directory

* characterSpecial.......Character oriented device

* blockSpecial.............. Block oriented device

* fifo...................................Named pipe

* link..................................Symbolic link

* socket............................Named socket

% file type myfile

file

%

% file type mydir

directory

%


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File lstat

Syntax: file lstat name varName

This returns the same information returned by the system call lstat. The results are placed in the

associative array varName. The indexes in varName are:

* atime.......time of last access* ctime.......time of last file status change

* dev...........inode's device

* gid............group ID of the file's group

* ino............inode's number

* mode.......inode protection mode

* mtime.....time of last data modification

* nlink........number of hard links

* size...........file size, in bytes

* type..........Type of File

* uid.............user ID of the file's owner Because this calls lstat, if name is a symbolic link,

the values in varName will refer to the link, not the file that is linked to.

file stat

Syntax: file stat name varName

This returns the same information returned by the system call stat. The results are placed in the

associative array varName. The indexes in varName are:

* atime.......time of last access

* ctime.......time of last file status change

* dev...........inode's device

* gid............group ID of the file's group* ino............inode's number

* mode.......inode protection mode

* mtime.....time of last data modification

* nlink........number of hard links

* size...........file size, in bytes

* type..........Type of File

* uid.............user ID of the file's owner


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38

File System

file readlink

Syntax: file readlink name

Returns the name of the file a symlink is pointing to. If name isn't a symlink, or can't be read, an error isgenerated.

% file readlink myfile

could not readlink "myfile": invalid argument

%

% ln -s myfile linkfile

%

% file readlink linkfile

myfile

%

file copySyntax: file copy ?--force? sourcePath targetPath

Copies a file from the source path to the target. Will not overwrite a file unless the --force option is

provided.

% file copy myfile myfile1

%

% file copy myfile myfile1

error copying "myfile" to "myfile1": file already exists

%

% file copy -force myfile myfile1

%

file rename

Syntax: file rename ?--force? sourcePath targetPath

Moves a file from the source path to the target. Will not overwrite a file unless the --force option is

provided.

% ls

myfile myfile1

%

% file rename myfile myfile2

%% file rename myfile1 myfile2

error renaming "myfile1" to "myfile2": file already exists

%

% file rename -force myfile1 myfile2

% ls

myfile2

%


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file delete

Syntax: file delete ?--force? path

Deletes a file or directory from the filesystem.

% ls

mydir myfile2%

% file delete myfile2

%

% ls

mydir

%

file mkdir

Syntax: file mkdir ?--force? path

Creates a new folder.

% ls

myfile

%

% file mkdir mydir

%

% ls

mydir myfile

%

File and Path Names

file dirname

Syntax: file dirname name

Returns the directory portion of a path/filename string. If name contains no slashes, file dirname returns

a ".". If the last "/" in name is also the first character, it returns a "/".

% file dirname /home/testuser/testdir

/home/testuser

%% file dirname /root/mydir

/root

%


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file extension

Syntax: file extension name

Returns the file extension.

% file extension test.sh

.sh%

% file extension test.tcl

.tcl

%

file rootname

Syntax: file rootname name

Returns all of the characters in nameup to but not including the last . character in the last component

of name. If the last component ofname does not contain a dot, then returns name.

% file rootname /root/test.dir/test.dir/root/test.dir/test

%

% file rootname /home/testuser/testdir

/home/testuser/testdir

%

file tail

Syntax: file tail name

Returns all of the characters in name after the last slash. Returns $name if name contains no slashes.

% file tail /root/Desktop/mydir/myfile

myfile

%

file nativename

Syntax: file nativename path

Returns the native name of a file. Useful when using exec to invoke a platform-native application that

requires a pathname in the platform's format.

% file nativename ~/example.txt/root/example.txt

%


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file normalize

Syntax: file normalize path

Returns an absolute path without any "../", or "./" components.

% ls ../myfile

../myfile%

% file normalize ../myfile

/root/myfile ------------ returns full path

%

file split

Syntax: file split path

Splits a path into a list in which each list element is a folder name the last element may be a file name.

% file split /home/testuser/testdir/testfile

/ home testuser testdir testfile%

file join

Syntax: file join list

Converts a list of folders into a platform-native file path.

% file join / home testuser testdir testfile

/home/testuser/testdir/testfile

%

% file join home testuser testdir testfile

home/testuser/testdir/testfile

%

file attributes

Syntax#1 file attributes name

% file attributes myfile

-group root -owner root -permissions 00644

%

Syntax#2 file attributes name ?option?

% file attributes myfile -group

root

%

% file attributes myfile -permissions

00644

%


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Syntax#3 file attributes name ?option? value option value...?

% file attributes myfile -permissions 00755

%

% file attributes myfile -permissions

00755

%

file link

Syntax: file link ?-linktype? linkName ?target?

If only one argument is given, that argument is assumed to be linkName, and this command returns the

value of the link given by linkName (i.e. the name of the file it points to). IflinkName is not a link or its

value cannot be read , then an error is returned.

% lsmyfile

%

% ln -s myfile linkfile

%

% file link linkfile

myfile

%

% file link -symbolic link2 myfile

myfile

%

%

% ls

link2 linkfile myfile

%

file pathtype

Syntax: file pathtype nameIfname refers to a specific file on a specific volume, the path type will be absolute.Ifname refers to a file relative to the current working directory, then the path type will be relative.Ifname refers to a file relative to the current working directory on a specified volume, or to a specificfile on the current working volume, then the path type is volumerelative.

% file pathtype ./myfile

relative

%

% file pathtype /root/myfile

absolute

%


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file separator

Syntax: file separator ?name?

If no argument is given, returns the character which is used to separate path segments for native files on

this platform.

% file separator

/%

If a path is given, the filesystem responsible for that path is asked to return its separator character. If no

file system accepts name, an error is generated.

file system

Syntax: file system name

% file system /dev/hda2

native%

file volumes

Syntax: file volumes

Returns the absolute paths to the volumes mounted on the system, as a proper Tcl list. Without anyvirtual filesystems mounted as root volumes, on UNIX, the command will always return /, since allfilesystems are locally mounted.

% file volumes

/

%

In Windows:

puts [file volumes]

A:/ C:/ D:/ M:/

Exec

Syntax: exec ?switches? arg1 ?arg2? ... ?argN? --- switch values are -keepnewline and --

% set a [exec ls]

mydir

myfile

test.sh%

% puts $a

mydir

myfile

test.sh

%


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Info Commands

Syntax: info option ?arg arg ...?

info argsSyntax: info args procname

Returns a list containing the names of the arguments to procedure procname, in order. Procname must

be the name of a Tcl command procedure.

% proc add { arg1 arg2} {

return [expr $arg1+$arg2]

}

%

% info args add

arg1 arg2

%

info body

Syntax: info body procname

Returns the body of procedureprocname. Procname must be the name of a Tcl command procedure

% info body add

return [expr $arg1+$arg2]

%

info cmdcount

Syntax: info cmdcount

Returns a count of the total number of commands that have been invoked in this interpreter.

% info cmdcount

358

% info cmdcount

366

%


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45

info commands

Syntax: info commands ?pattern?

Ifpattern isn't specified, returns a list of names of all the Tcl commands in the current namespace,

including both the built-in commands written in C and the command procedures defined using the proc

command.Ifpattern is specified, only those names matchingpattern are returned.

% info commands

tell socket subst open eof pwd glob list exec pid auto_load_index time unknown eval lrange fblocked

lsearch auto_import gets case lappend proc break variable llength auto_execok return linsert error catch

clock info split array if fconfigure concat join lreplace add source fcopy global switch auto_qualify

update close cd for auto_load file append format read package set binary namespace scan trace seek

while flush after vwait uplevel continue foreach lset rename fileevent regexp upvar unset encoding expr

load regsub history interp exit puts incr lindex lsort tclLog string

%

%

% info commands a*

auto_load_index auto_import auto_execok array add auto_qualify auto_load append after

%

In the above output add is defined by us in the previous step.

info exists

Syntax: info exists varName

Returns 1 if the variable named varName exists in the current context (either as a global or local

variable), returns 0 otherwise.

% info exists var

0

%

% set var 10

10

%

% info exists var

1

%

info complete

Syantax: info comlete string

If string has no unmatched brackets, braces or parentheses, then a value of 1 is returned, else 0 is

returned.

% set cmd { puts "hello world}

% info complete $cmd

0

% set cmd { puts "hello world}; info complete $cmd; --------> Returns 1


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info globals

Syntax: info globals ?pattern?

Ifpattern isn't specified, returns a list of all the names of currently-defined global variables. Global

variables are variables in the global namespace. Ifpattern is specified, only those names

matchingpattern are returned.

% set var 10

10

%% set a 5

5

% proc test { } {

global a

return $a

}

%

% info globals

tcl_rcFileName tcl_version argv0 argv tcl_interactive a var auto_oldpath errorCode auto_path errorInfo

auto_index env tcl_pkgPath tcl_patchLevel argc tcl_libPath tcl_library tcl_platform

%

info hostname

Syntax: info hostname

Returns the name of the computer on which this invocation is being executed.

% info hostname

localhost

%

info library

Syntax: info library

Returns the name of the library directory in which standard Tcl scripts are stored.

% info library

/usr/share/tcl8.4

%

info nameofexecutableSyntax: info nameofexecutable

Returns the full path name of the binary file from which the application was invoked.

% info nameofexecutable

/usr/bin/tclsh

%


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47

info patchlevel

info patchlevel

Returns the value of the global variable tcl_patchLevel

% info patchlevel

8.4.13

%

info procs

Syntax: info procs ?pattern?

Returns a list of all the names of Tcl command procedures in the current namespace.

% info procs

auto_load_index test unknown auto_import auto_execok add auto_qualify auto_load history tclLog

%

% info procs t*

test tclLog

%

info script

Syntax: info script

If a Tcl script file is currently being evaluated.

info sharedlibextension

Syntax: info sharedlibextension

Returns the extension used on this platform for the names of files containing shared libraries.

% info sharedlibextension

.so

%

info tclversion

Syntax: info tclversion

Returns the value of the global variable tcl_version

% info tclversion

8.4

%

info vars

Syntax: info vars ?pattern?Returns a list of all the names of currently-visible variables.

% info vars

tcl_rcFileName tcl_version argv0 argv tcl_interactive a var b auto_oldpath errorCode auto_path

errorInfo auto_execs auto_index env tcl_pkgPath tcl_patchLevel argc tcl_libPath tcl_library tcl_platform

%

% info vars a*

argv0 argv a auto_oldpath auto_path auto_execs auto_index argc


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Source command

Syntax: sourcefilename

The source command will load a file and execute it.

This command can be used to:

separate a program into multiple files. make a library file that contains all the procs for a particular set of functions. configure programs load data files

% cat test.tcl

puts "hello world"

puts "This is sample tcl program"

%% source test.tcl

hello world

This is sample tcl program

%

Package Commands

Tcl supports grouping multiple procedures or compiled "C" code modules into a single entity referred to

as a package. A package may consist of a single file, multiple files or a mix of compiled and Tcl scriptfiles.

To access a package from a script:

1 Make certain that the auto_path global variable includes the path to the package you

wish to include. The standard Tcl distributions include the proper paths by default.

2 Include a line like this in the application that uses a package:

package require nameOfPackage

You script will need a separate package require command for each package you wish to include.

To create a package, you'll need

1 to include a package provide command likepackage provide nameOfPackage revisionNumber

in each file that's included in the package

2 create a pkgIndex.tcl file to describe the files in the package.

This can be done with the pkg_mkIndex command.


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package provide

Syntax: package provide name revision

Declares that this file provides an implementation of a specific revision of a package. A file may include

only one package provide command.

%

% cat myfile.tcl

package provide demopkg 1.0

proc demoproc {} {

puts "Running the demoproc"

}

proc add { a b } {

set c [expr $a + $b]

return $c

}

%

pkg_mkIndex

Syntax: pkg_mkIndex libdir file1 ... filen

Creates an index file (pkgIndex.tcl) in libdir from the source code modules listed as file1 - filen. Each proc

in the files will be listed in the index file, with a reference to the source code module that contains it.

% pkg_mkIndex /root/mydir myfile.tcl

%

package require

Syntax: package require name ?revision?

Tells the interpreter to find a package with the given name and optional revision number. If the revision

number is absent, the largest revision available is used.

% add 2 3

invalid command name "add"

%

% lappend auto_path /root/mydir

/usr/share/tcl8.4 /usr/share /usr/lib /root/mydir%

% package require demopkg

1.0

%

% add 2 3

5

%


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50

Eval Command

Syntax: eval arg1 ??arg2?? ... ??argn??

Evaluates arg1 - argn as one or more Tcl commands. The args are concatenated into a string, and

passed to tcl_Eval to evaluate and execute.

Eval returns the result (or error code) of that evaluation.

The eval command will evaluate a list of strings as though they were commands typed at the % prompt

or sourced from a file.

% set i "set j 2"

set j 2

%

% set j

can't read "j": no such variable

%

% eval $i

2

%

% puts $j

2

% set i 1

1

%

% eval puts $i

1%

% eval puts hello

hello

%

% eval puts "hello wolrd" --------------------------------------> This is error case.

can not find channel named "hello"

%

% eval [list puts {hello world}] --------------------------------> Method-1

hello world

%

% eval [format {%s "%s"} puts "hello world"] --------------> Method-2

hello world

%


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51

Subst Command

Syntax: subst ?-nobackslashes? ?-nocommands? ?-novariables? String

If any of the -no... arguments are present, then that set of substitutions will not be done.

The Tcl interpreter does only one substitution pass during command evaluation. Some situations, suchas placing the name of a variable in a variable, require two passes through the substitution phase. In this

case, the subst command is useful.

Subst performs a substitution pass without performing any execution of commands except those

required for the substitution to occur, ie: commands within [] will be executed, and the results placed in

the return string.

% set a 1

1

% set c a

a

%

% puts $$c

$a

%

% puts [subst $$c]

1

%

% puts "format with no subst [format {$%s} $c]"

format with no subst $a

%

% puts "format with subst: [subst [format {$%s} $c]]"

format with subst: 1%

% set a arrayname

% set b index

% set c newvalue

% eval [format "set %s(%s) %s" $a $b $c]

% puts "Index: $b of $a was set to: $arrayname(index)"

Index: index of arrayname was set to: newvalue


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