slipstream81
asked on
Bash scripting - escaping variable substitute in eval
In the following script:
#!/bin/sh
# file count
lc=`cat integrit.log |grep 'changed:' | awk '{print $2}' | wc -l`
# run count
rc=1
odir="/export/export/www/o
while [ $lc -ge $rc ]; do
curfile=`eval cat integrit.log | grep 'changed:' | awk 'NR==$rc {print $2}'`
oldfile=$odir$curfile
echo "Changes in $curfile compared to $oldfile"
diff $curfile $oldfile
rc=`expr $rc + 1`
done
I'd like to have the $2 in the awk script (curfile=..) escaped, but the $rc substituted.
escaping like \$2 doesn't seem to work, nor does curfile=`cat integrit.log | grep 'changed:' | awk 'NR==$(eval $rc) {print $2}'`
Help?
#!/bin/sh
# file count
lc=`cat integrit.log |grep 'changed:' | awk '{print $2}' | wc -l`
# run count
rc=1
odir="/export/export/www/o
while [ $lc -ge $rc ]; do
curfile=`eval cat integrit.log | grep 'changed:' | awk 'NR==$rc {print $2}'`
oldfile=$odir$curfile
echo "Changes in $curfile compared to $oldfile"
diff $curfile $oldfile
rc=`expr $rc + 1`
done
I'd like to have the $2 in the awk script (curfile=..) escaped, but the $rc substituted.
escaping like \$2 doesn't seem to work, nor does curfile=`cat integrit.log | grep 'changed:' | awk 'NR==$(eval $rc) {print $2}'`
Help?
ASKER
I solved this on my own, just used a more logical method. Shell scripting is not my forte either ;)
#!/bin/sh
odir="/export/export/www/o
for n in `cat integrit.log | grep 'changed:' | awk '{print $2}'`; do
curfile=$n
oldfile=$odir$curfile
echo "Changes in $curfile compared to $oldfile"
diff $curfile $oldfile
done
#!/bin/sh
odir="/export/export/www/o
for n in `cat integrit.log | grep 'changed:' | awk '{print $2}'`; do
curfile=$n
oldfile=$odir$curfile
echo "Changes in $curfile compared to $oldfile"
diff $curfile $oldfile
done
You solved it another way but here is a possible solution
to evaluate $rc but not $2 : concatenate a double-quoted string and a single quoted-string, ie :
rc=somevalue
somecommand | awk "NR==$rc"' {print $2}'
Stephane
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jmcg
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I will leave the following recommendation for this question in the Cleanup topic area:
PAQ with points refunded
Please leave any comments here within the next seven days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
jmcg
EE Cleanup Volunteer
ASKER CERTIFIED SOLUTION
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It is generally easier to read if you use the more modern $(command) syntax instead of `command` (backquotes). This syntax is also nestable.
I don't know the solution to the escaping problem; shell language is not my forte. I just thought I would add the above.