Shell Programming and Scripting

Hello,

I am trying the following:
echo __CHANGEME__ >> testfile
VAR1="&&&"
sed -i "s|__CHANGEME__|${VAR1}|" testfile
cat testfile

This results in testfile containing
__CHANGEME____CHANGEME____CHANGEME__

Whereas I want it to result in
&&&

I understand that if
VAR1="\&\&\&"
then it would work.

But this is a simplified version of my script. In my actual script VAR1 is coming in as a user input/randomly generated ASCII string.

I also understand that I can write some code to insert escape characters in "VAR1". But I am hoping that there a more intelligent way to do this using sed only. For some reason '&' is the only special character that is causing problems.

Thanks in advance for your input.

Hi,
try using perl

perl -pi -e 's/__CHANGEME__/'$var1'/' testfile

Bye

Hi Sauron,

Your suggestion works perfectly. However since I am trying to learn sed, I would still appreciate if some sed experts could shed some light on this. Is it possible to do this using sed, or is this just a sed limitation that I should make a mental note of for the future.

Thanks.

You could try to escape your replacement string with backslashes before:

Code:

echo __CHANGEME__ >> testfile
print - "Enter VAR1:" ; read VAR1
VAR1="$(print - "$VAR1" | sed 's/[&=\|]/\&/g')"
sed -i 's|__CHANGEME__|'"${VAR1}"'|' testfile
cat testfile

Btw., i have changed your quotations a bit to make the script more robust. I have included only four metacharacters ("\", "&", "=", "|") to be escaped but you can easily expand the expression to make it more general. In any case you will have to escape your delimiting char, which is "|" here.

I hope this helps.

bakunin