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Basic bash scripting

Posted on 2012-12-24
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Last Modified: 2013-01-26
Getting into the basics of bash scripting, one thing I'm looking at is numerical comparisons.

I have the following code:

#!/bin/sh

current=`cat /root/VERSION.OLD`
new=`cat /root/VERSION`



if [["$current" -lt "$new"]]; then
echo "current is less than new"
echo "current is " $current
echo "new is " $new


else
echo "current is newer than new"
echo "current is " $current
echo "new is " $new
fi

Output is:

[root@dev ~]# sh rvtest
rvtest: line 8: [[201212241235: command not found
current is newer than new
current is  201212241235
new is  201212241236

Why the error? It's also not doing the comparison.

Line 8 is: if [["$current" -lt "$new"]]; then
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Question by:rvcw
2 Comments
 
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Accepted Solution

by:
ozo earned 1000 total points
ID: 38719406
if [["$current" -lt "$new"]]; then
should be
if [[ "$current" -lt "$new" ]]; then
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LVL 31

Assisted Solution

by:farzanj
farzanj earned 1000 total points
ID: 38719446
As Ozo said, there should be spaces before ]] and after [[.

With [[ ]] you should use < instead of -lt in the Borne style.
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