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Top Forums Shell Programming and Scripting Increment a variable in unix bash Post 302629185 by radoulov on Tuesday 24th of April 2012 11:42:42 AM
Old 04-24-2012
If it's bash, it shouldn't throw an error with this code Smilie

Code:
$ bash -c 'echo $BASH_VERSION; (( c += 3 )); echo $c'
3.2.25(1)-release
3

Notice that the standard/POSIX syntax is different:

Code:
c=$(( c + 1 ))

But bash has various extensions.
 

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incr(1T)						       Tcl Built-In Commands							  incr(1T)

__________________________________________________________________________________________________________________________________________________

NAME
incr - Increment the value of a variable SYNOPSIS
incr varName ?increment? _________________________________________________________________ DESCRIPTION
Increments the value stored in the variable whose name is varName. The value of the variable must be an integer. If increment is supplied then its value (which must be an integer) is added to the value of variable varName; otherwise 1 is added to varName. The new value is stored as a decimal string in variable varName and also returned as result. EXAMPLES
Add one to the contents of the variable x: incr x Add 42 to the contents of the variable x: incr x 42 Add the contents of the variable y to the contents of the variable x: incr x $y Add nothing at all to the variable x (often useful for checking whether an argument to a procedure is actually numeric and generating an error if it is not): incr x 0 SEE ALSO
expr(1T) KEYWORDS
add, increment, variable, value ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWTcl | +--------------------+-----------------+ |Interface Stability | Uncommitted | +--------------------+-----------------+ NOTES
Source for Tcl is available on http://opensolaris.org. Tcl incr(1T)
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