Section: User Commands (1)
Updated: March 2007
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expr - evaluate expressions
display this help and exit
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.
Written by Mike Parker.
Report bugs to <firstname.lastname@example.org>.
Copyright © 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
is maintained as a Texinfo manual. If the
programs are properly installed at your site, the command
should give you access to the complete manual.
- REPORTING BUGS
- SEE ALSO
linux.jgfs.net manual pages