expr - evaluate expressions
--help display this help and exit
Print the value of EXPRESSION to standard output. A blank line below separates increasing precedence groups. EXPRESSION may be:
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 of STRING
keyword like ‘match’ or an operator like ‘/’
Beware that many operators need to be escaped or quoted for shells. Comparisons are arithmetic if both ARGs are numbers, else lexicographical. Pattern matches return the string matched between \( and \) or null; if \( and \) are not used, they return the number of characters matched or 0.
Exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null or 0, 2 if EXPRESSION is syntactically invalid, and 3 if an error occurred.
Written by Mike Parker.
Report bugs to <firstname.lastname@example.org>.
Copyright (C) 2006 Free Software Foundation, Inc. This is free software. You may redistribute copies of it under the terms of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the extent permitted by law.
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
should give you access to the complete manual.
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