Remote sed to change file is failing

Question

I have the following script that defines an OLD and a NEW string. I want to replace the OLD with the NEW using sed over a remote connection. All the commands besides the sed appear to be working. I have tried adjusting punctuation and using pipes instead of forward slashes with sed to no avail. Doing the sed command from a command prompt works, but within the script, it does not. I would appreciate any input on this.

#!/bin/ksh

OLD="command\[Check_Memory_OS_10038\]=/opt/tools/nagitem/libexec/check_mem.pl -w 80,10 -c 90,25";export OLD
NEW="command\[Check_Memory_OS_10038\]=/opt/tools/nagitem/libexec/check_mem_ng.sh -w 80 -c 90";export NEW
DEST1="/opt/tools/nagitem/libexec/"
DEST2="/opt/tools/nagitem/nrdp/clients/nrds/"

for x in `cat /home/joe/nagios/hostlist`
do
SSH_STATUS=$(ssh -n -o BatchMode=yes -o StrictHostKeyChecking=no $USER@$x "pwd" >/dev/null)
  if [[ $? = "0" ]];then
    scp -p /home/joe/nagios/check_mem_ng.sh $x:/tmp
    ssh -o "StrictHostKeyChecking no" $x "sudo /usr/localcw/bin/eksh -c '/bin/cp /tmp/check_mem_ng.sh $DEST1;chown nagitem:nagitem $DEST1/check_mem_ng.sh;cd $DEST2; /bin/sed -i -e 's/'$OLD'/'$NEW'/g' /opt/tools/nagitem/nrdp/clients/nrds/nrds.cfg '"
else
   echo "Cannot connect to $x" >> badhosts
fi
done

Error received is: /bin/sed: -e expression #1, char 39: unknown option to `s'

Answer 1

This code of yours required an overhaul in a couple of places.

• The initializations of environment vars $OLD n $NEW to use no escaping as they get backslash ed downstream, lest they be double escaped.
• Escape $OLD var so that it becomes saf e for plug in on the LHS of a sed substitute command.
• Similarly, Escape the $NEW var for use on RHS of the substitute command.
• The sed command is using single quotes within single quotes under the overall umbrella of double quotes , so they were escaped taking care to escape any single quotes within new or old var values too.

#!/bin/ksh

OLD="command[Check_Memory_OS_10038]=/opt/tools/nagitem/libexec/check_mem.pl -w 80,10 -c 90,25";export OLD
NEW="command[Check_Memory_OS_10038]=/opt/tools/nagitem/libexec/check_mem_ng.sh -w 80 -c 90";export NEW
DEST1="/opt/tools/nagitem/libexec/"
DEST2="/opt/tools/nagitem/nrdp/clients/nrds/"

#--------------------
# escape variables
eOLD=$(printf '%s\n' "$OLD" | sed -e 's:[][\/^$.*]:\\&:g' -e "s:':&\\&&:g")
eNEW=$(printf '%s\n' "$NEW" | sed -e 's:[\/&]:\\&:g' -e "s:':&\\&&:g")
#--------------------

for x in `cat /home/joe/nagios/hostlist`
do
SSH_STATUS=$(ssh -n -o BatchMode=yes -o StrictHostKeyChecking=no $USER@$x "pwd" >/dev/null)
  if [[ $? = "0" ]];then
    scp -p /home/joe/nagios/check_mem_ng.sh $x:/tmp
    ssh -o "StrictHostKeyChecking no" $x "sudo /usr/localcw/bin/eksh -c '/bin/cp /tmp/check_mem_ng.sh $DEST1;chown nagitem:nagitem $DEST1/check_mem_ng.sh;cd $DEST2; /bin/sed -i -e '\\''s/$eOLD/$eNEW/g'\\'' /opt/tools/nagitem/nrdp/clients/nrds/nrds.cfg'"
else
   echo "Cannot connect to $x" >> badhosts
fi
done

Answer 2

You quote your eksh parameter with single quotes '. Inside single quotes, there is no possibility to expand special characters. So your $DEST and other variables are not expanded, leaving some weird residuals.