I am trying to replace a string in a file on a remote server:
ssh $login "
replacement=\`find . -name file\`;
sed -i -e 's/contact/\$replacement/g' path/file;
"
but I can't get the content of the $replacement variable to be used by sed. The example above prints $replacement in my file. I also tried
sed -i -e 's/contact/\"\$replacement\"/g' path/file;
but it just prints "$replacement"
What would be the correct syntax?
The problem is that in between single quotes $replacement isn't expanded.
In this case sed -i -e "s/contact/$replacement/g" path/file; should work.
Or this:
sed -i -e 's/nothing/'$replacement'/g' path/file;
Example:
$ echo "There's nothing there." > file
$ cat file
There's nothing there.
$ replacement=something
$ sed -i -e 's/nothing/'$replacement'/g' file;
$ cat file
There's something there.
In response to Kusalananda's comment below: If replacement, being a path, contains slashes then you would have to pre-process it before you use it with sed:
replacement=$(sed 's@\/@\\\/@g' <<< "$replacement")
$replacement may be a pathname, i.e. it may (will!) contain slashes. Also, you should demonstrate running this on a remote machine using ssh. Using localhost for testing would be enough.
sed can use almost any other character as delimiter instead of / in a substitution. sed 's@PATTERN@REPLACEMENT@', for example. The only thing is to make sure it's not a character already in the pattern, or in the replacement.
here documents are a good idea to explore when you're in quoting hell:
ssh "$login" <<'END_REMOTE'
replacement=$(find . -name file)
sed -i -e 's/contact/$replacement/g' path/file
END_REMOTE
The opening keyword for the heredoc is quoted, which means the whole heredoc is single quoted. Easier to read, no?
sedexpression, including the variable expansion. This will prevent the shell from expanding your variable. Could you confirm that you want to replace the stringcontactin some file with the pathnames of a set of files?