Question

I am trying to substitute few special characters using sed/perl for which I am getting errors.

In below command i am trying to replace values for SEARCHFIELDAPP, OLD_STRING,NEW_STRING etc;

Server1> SERVER_COMMAND="perl -F'\|' -i -lape  'if (\$F[0] eq \"SEARCHFIELDAPP\" && \$F[1] eq \"SEARCHFIELDDB\" && \$F[6] eq \"SEARCHFIELDUNM\" )  { s/\|OLD_STRING\|/\|NEW_STRING\|/g; s/\|LAST_UPDATE_DT/\|CURR_UPDATE_DT/g }' " 

Above command is as shown below when printed on console.

Server1> echo $SERVER_COMMAND
perl -F'\|' -i -lape 'if ($F[0] eq "SEARCHFIELDAPP" && $F[1] eq "SEARCHFIELDDB" && $F[6] eq "SEARCHFIELDUNM" ) { s/\|OLD_STRING\|/\|NEW_STRING\|/g; s/\|LAST_UPDATE_DT/\|CURR_UPDATE_DT/g }'

In above command string, I am trying to replace few Strings:

Server1> echo $SERVER_COMMAND | sed -e "s|SEARCHFIELDAPP|ALLOWSERVICE|;s|SEARCHFIELDDB|DataDup|;s|SEARCHFIELDUNM|mogga|;s|OLD_STRING|mogga_dev_$%^|;s|NEW_STRING|mogga&*%^$|;s|LAST_UPDATE_DT|09-21-2012:11:09:41|;s|CURR_UPDATE_DT|09-21-2012:11:18:17|;"

When I do that I am getting an output as shown below:

perl -F'\|' -i -lape 'if ($F[0] eq "ALLOWSERVICE" && $F[1] eq "DataDup" && $F[6] eq "mogga" ) { s/\|mogga_dev_$%^\|/\|moggaNEW_STRING*%^$\|/g; s/\|09-21-2012:11:09:41/\|09-21-2012:11:18:17/g }'

Problem here is with substitution s|NEW_STRING|mogga&*%^$|; . I was expecting NEW_STRING to be replaced with mogga&*%^$ but it is getting replaced with moggaNEW_STRING*%^$.

Here & is getting interpreted as NEW_STRING. When I escape &, it works fine. But I get this string from a parent script which i use in child script dynamically. I am looking for some way to successfully substitute string as it is, without escaping any character. Escaping will make me to modify incoming string with escape character which i want to avoid.

I tried the same by using perl one liner for substitution. But here also i am facing similar issue with special character.

Server1> echo $SERVER_COMMAND |  perl -p -i -e 's|SEARCHFIELDAPP|ALLOWSERVICE|;s|SEARCHFIELDDB|DataDup|;s|SEARCHFIELDUNM|mogga|;s|OLD_STRING|mogga_dev_$%^|;s|NEW_STRING|mogga&*%^|;s|LAST_UPDATE_DT|09-21-2012:11:09:41|;s|CURR_UPDATE_DT|09-21-2012:11:18:17|;'

Below is how it looks after substitution:

perl -F'\|' -i -lape 'if ($F[0] eq "ALLOWSERVICE" && $F[1] eq "DataDup" && $F[6] eq "mogga" ) { s/\|mogga_dev_0^\|/\|mogga&*%^\|/g; s/\|09-21-2012:11:09:41/\|09-21-2012:11:18:17/g }'

I am seeing string OLD_STRING which was suppose to get replaced with string mogga_dev_$%^ got replaced with mogga_dev_0^. Here $% is getting converted to 0

In this case as well i get what expect by escaping problematic characters.

Can you please let me know how to avoid this interpretation apart from escaping special characters?

Thanks

---

After William’s inputs I was able to achieve below without errors:

perl -F'\|' -i -lape 'if ($F[0] eq "ALLOWSERVICE" && $F[1] eq "DataDup" && $F[6] eq "mogga" ) { s/\|mogga_dev_!$%^\|/\|mogga!&*%^$@*&^%\|/g; s/\|09-21-2012:11:09:41/\|09-21-2012:11:18:17/g }'

But when I execute this on a file for substitution. I am not seeing string mogga_dev_!$%^ is not getting replaced with mogga!&%^$@&^% in the file.

Since special characters are not escaped, I think replacement is not happening. But I dont want to use escaping to escape special characters. Can you please help me with some other method in replacing string with special characters in file?

Thanks

Answer 1

In perl, a simple way to avoid any interpolation is to use ' as the delimiter. eg.

perl -pe "s'OLD_STRING'mogga_dev_\$%^'"

In this case, we must escape the $ to get the string mogga_dev_$%^ into perl, but perhaps this can help you. It’s not clear to me exactly which strings you are trying to avoid adding escape characters to, and if you have the string mogga_dev_$%^ in a string NEW_STRING, you can do:

perl -pe "s'"$OLD_STRING"'"$NEW_STRING"'"