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EXPR

Section: User Commands (1)
Updated: September 2017
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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 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.

AUTHOR

Written by Mike Parker, James Youngman, and Paul Eggert.

REPORTING BUGS

GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Report expr translation bugs to <http://translationproject.org/team/>

COPYRIGHT

Copyright © 2017 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.