Reference

Backslash Sequences

Table 1-1. Backslash sequences

\a	Bell. (0x7)
\b	Backspace. (0x8)
\f	Form feed. (0xc)
\n	Newline. (0xa)
\r	Carriage return. (0xd)
\t	Tab. (0x9)
\v	Vertical tab. (0xb)
\<newline>	Replace the newline and the leading white space on the next line with a space.
\\	Backslash. ('\')
\ooo	Octal specification of character code. 1, 2, or 3 octal digits (0-7).
\xhh	Hexadecimal specification of character code. 1 or 2 hex digits. Be careful when using this in a string of characters, because all hexadecimal characters following the \x will be consumed, but only the last 2 will specify the value.
\uhhhh	Hexadecimal specification of a 16-bit Unicode character value. 4 hex digits.
\c	Replaced with literal c if c is not one of the cases listed above. In particular, \$, \", \{, \}, \], and \[ are used to obtain these characters.

Arithmetic Operators

Table 1-2. Arithmetic operators from highest to lowest precedence

- ~ !	Unary minus, bitwise NOT, logical NOT.
* / %	Multiply, divide, remainder.
+ -	Add, subtract.
<< >>	Left shift, right shift.
< > <= >=	Comparison: less, greater, less or equal, greater or equal.
== != eq ne	Equal, not equal, string equal (Tcl 8.4), string not equal (Tcl 8.4).
&	Bitwise AND.
^	Bitwise XOR.
|	Bitwise OR.
&&	Logical AND.
||	Logical OR.
x?y:z	If x then y else z.

Built-in Math Functions

Table 1-3. Built-in math functions

acos(x)	Arccosine of x.
asin(x)	Arcsine of x.
atan(x)	Arctangent of x.
atan2(y,x)	Rectangular (x,y) to polar (r,th). atan2 gives th.
ceil(x)	Least integral value greater than or equal to x.
cos(x)	Cosine of x.
cosh(x)	Hyperbolic cosine of x.
exp(x)	Exponential, ex.
floor(x)	Greatest integral value less than or equal to x.
fmod(x,y)	Floating point remainder of x/y.
hypot(x,y)	Returns sqrt(x*x + y*y). r part of polar coordinates.
log(x)	Natural log of x.
log10(x)	Log base 10 of x.
pow(x,y)	x to the y power, xy.
sin(x)	Sine of x.
sinh(x)	Hyperbolic sine of x.
sqrt(x)	Square root of x.
tan(x)	Tangent of x.
tanh(x)	Hyperbolic tangent of x.
abs(x)	Absolute value of x.
double(x)	Promote x to floating point.
int(x)	Truncate x to an integer.
round(x)	Round x to an integer.
rand()	Return a random floating point value between 0.0 and 1.0.
srand(x)	Set the seed for the random number generator to the integer x.
wide(x)	Promote x to a wide (64-bit) integer. (Tcl 8.4)

Core Tcl Commands

The pages listed in Table 1-4 give the primary references for the command.

Table 1-4. Built-in Tcl commands

Command	Pg.	Description
after	228	Schedule a Tcl command for later execution.
append	56	Append arguments to a variable's value. No spaces added.
array	97	Query array state and search through elements.
binary	59	Convert between strings and binary data.
break	83	Exit loop prematurely.
catch	83	Trap errors.
cd	122	Change working directory.
clock	183	Get the time and format date strings.
close	121	Close an open I/O stream.
concat	65	Concatenate arguments with spaces between. Splices lists.
console	29	Control the console used to enter commands interactively.
continue	83	Continue with next loop iteration.
error	85	Raise an error.
eof	116	Check for end of file.
eval	130	Concatenate arguments and evaluate them as a command.
exec	105	Fork and execute a UNIX program.
exit	124	Terminate the process.
expr	6	Evaluate a math expression.
fblocked	233	Poll an I/O channel to see if data is ready.
fconfigure	231	Set and query I/O channel properties.
fcopy	250	Copy from one I/O channel to another.
file	108	Query the file system.
fileevent	229	Register callback for event-driven I/O.
flush	116	Flush output from an I/O stream's internal buffers.
for	82	Loop construct similar to C for statement.
foreach	79	Loop construct over a list, or lists, of values.
format	56	Format a string similar to C sprintf.
gets	119	Read a line of input from an I/O stream.
glob	122	Expand a pattern to matching file names.
global	90	Declare global variables.
history	196	Use command-line history.
if	76	Test a condition. Allows else and elseif clauses.
incr	12	Increment a variable by an integer amount.
info	186	Query the state of the Tcl interpreter.
interp	292	Create additional Tcl interpreters.
join	72	Concatenate list elements with a given separator string.
lappend	66	Add elements to the end of a list.
lindex	68	Fetch an element of a list.
linsert	68	Insert elements into a list.
list	65	Create a list out of the arguments.
llength	68	Return the number of elements in a list.
load	697	Load shared libraries that define Tcl commands.
lrange	68	Return a range of list elements.
lreplace	68	Replace elements of a list.
lsearch	69	Search for an element of a list that matches a pattern.
lset	62	Set an element in a list. (Tcl 8.4)
lsort	70	Sort a list.
namespace	213	Create and manipulate namespaces.
open	116	Open a file or process pipeline for I/O.
package	175	Provide or require code packages.
pid	124	Return the process ID.
proc	87	Define a Tcl procedure.
puts	119	Output a string to an I/O stream.
pwd	122	Return the current working directory.
read	120	Read blocks of characters from an I/O stream.
regexp	158	Match regular expressions.
regsub	162	Substitute based on regular expressions.
rename	88	Change the name of a Tcl command.
return	86	Return a value from a procedure.
scan	58	Parse a string according to a format specification.
seek	121	Set the seek offset of an I/O stream.
set	5	Assign a value to a variable.
socket	239	Open a TCP/IP network connection.
source	26	Evaluate the Tcl commands in a file.
split	71	Chop a string up into list elements.
string	49	Operate on strings.
subst	140	Substitute embedded commands and variable references.
switch	77	Test several conditions.
tell	121	Return the current seek offset of an I/O stream.
time	202	Measure the execution time of a command.
trace	193	Monitor variable assignments.
unknown	178	Handle unknown commands.
unset	13	Delete variables.
uplevel	138	Execute a command in a different scope.
upvar	91	Reference a variable in a different scope.
variable	207	Declare namespace variables.
vwait	230	Wait for a variable to be modified.
while	79	Loop until a boolean expression is false.