
expr — evaluate expressions
expr
EXPRESSION
expr
OPTION
−−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 if it is neither null nor 0, otherwise ARG2
ARG1 if neither argument is null or 0, otherwise 0
ARG1 is less than ARG2
ARG1 is less than or equal to ARG2
ARG1 is equal to ARG2
ARG1 is unequal to ARG2
ARG1 is greater than or equal to ARG2
ARG1 is greater than ARG2
arithmetic sum of ARG1 and ARG2
arithmetic difference of ARG1 and ARG2
arithmetic product of ARG1 and ARG2
arithmetic quotient of ARG1 divided by ARG2
arithmetic remainder of ARG1 divided by ARG2
anchored pattern match of REGEXP in STRING
same as STRING : REGEXP
substring of STRING, POS counted from 1
index in STRING where any CHARS is found, or 0
length of STRING
interpret TOKEN as a string, even if it is a
keyword like 'match' or an operator like '/'
value of EXPRESSION
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.
Report expr bugs to bug−coreutils@gnu.org
GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
General help using GNU software: <http://www.gnu.org/gethelp/>
Report expr translation bugs to <http://translationproject.org/team/>
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 coreutils 'expr invocation'
should give you access to the complete manual.
COPYRIGHT 

Copyright © 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. 