Shell Script - single line - expr command

Question

I am using this 3 line shell script and it works to compare 2 files sizes.

FIRSTV=`stat -c%s crk03-rtr-002-20140504.rsc`
SECONDV=`stat -c%s crk03-rtr-002-20140503.rsc`
echo `expr $FIRSTV - $SECONDV`

If there a way I could do this on 1 line using expr or a better command which can tell me the number of bytes differnce between 2 files?

L

Note that echo `expr $FIRSTV - $SECONDV` produces exactly the same output as expr $FIRSTV - $SECONDV; you don't need the echo or back-quotes. — Jonathan Leffler
– Jonathan Leffler, Commented May 4, 2014 at 8:02

anubhava · Accepted Answer · 2014-05-04 08:30:41Z

1

Yes you can do:

expr `stat -c%s crk03-rtr-002-20140504.rsc` - `stat -c%s crk03-rtr-002-20140503.rsc`

In BASH/ksh/dash and few more shells you can make use of (( )) (arithmetic evaluation brackets):

echo $(( $(stat -c%s crk03-rtr-002-20140504.rsc) - $(stat -c%s crk03-rtr-002-20140503.rsc) ))

answered May 4, 2014 at 7:50

anubhava

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1 Comment

Arithmetic expansion is not bash specific but part of the POSIX standard. Your second line would work with ksh, dash and others. pubs.opengroup.org/onlinepubs/9699919799/utilities/…