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Top Forums Shell Programming and Scripting Help it works but its to SLOW Post 302181455 by era on Thursday 3rd of April 2008 03:17:08 AM
Old 04-03-2008
The shell is not very good at arithmetic, so for small numbers, I prefer working with just a string -- grow the string by one character in the loop, and once the string is x characters long, quit. But here, obviously, the number is large enough that the traditional way of doing this is better.

Code:
n=0
while whatever; do
  n=`expr 1 + $n`
  case $n in *00) wait;; esac
  ... go on
done

 

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EXPR(1) 								FSF								   EXPR(1)

NAME
expr - evaluate expressions SYNOPSIS
expr EXPRESSION expr OPTION DESCRIPTION
--help display this help and exit --version output version information and exit Print the value of EXPRESSION to standard output. A blank line below separates increasing precedence groups. EXPRESSION may be: ARG1 | ARG2 ARG1 if it is neither null nor 0, otherwise ARG2 ARG1 & ARG2 ARG1 if neither argument is null or 0, otherwise 0 ARG1 < ARG2 ARG1 is less than ARG2 ARG1 <= ARG2 ARG1 is less than or equal to ARG2 ARG1 = ARG2 ARG1 is equal to ARG2 ARG1 != ARG2 ARG1 is unequal to ARG2 ARG1 >= ARG2 ARG1 is greater than or equal to ARG2 ARG1 > ARG2 ARG1 is greater than ARG2 ARG1 + ARG2 arithmetic sum of ARG1 and ARG2 ARG1 - ARG2 arithmetic difference of ARG1 and ARG2 ARG1 * ARG2 arithmetic product of ARG1 and ARG2 ARG1 / ARG2 arithmetic quotient of ARG1 divided by ARG2 ARG1 % ARG2 arithmetic remainder of ARG1 divided by ARG2 STRING : REGEXP anchored pattern match of REGEXP in STRING match STRING REGEXP same as STRING : REGEXP substr STRING POS LENGTH substring of STRING, POS counted from 1 index STRING CHARS index in STRING where any CHARS is found, or 0 length STRING length of STRING + TOKEN interpret TOKEN as a string, even if it is a keyword like `match' or an operator like `/' ( EXPRESSION ) value of EXPRESSION Beware that many operators need to be escaped or quoted for shells. Comparisons are arithmetic if both ARGs are numbers, else lexicograph- ical. Pattern matches return the string matched between ( and ) or null; if ( and ) are not used, they return the number of characters matched or 0. AUTHOR
Written by Mike Parker. REPORTING BUGS
Report bugs to <bug-coreutils@gnu.org>. COPYRIGHT
Copyright (C) 2002 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU- LAR PURPOSE. SEE ALSO
The full documentation for expr is maintained as a Texinfo manual. If the info and expr programs are properly installed at your site, the command info expr should give you access to the complete manual. GNU coreutils 4.5.3 February 2003 EXPR(1)
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