Insert contents of file into XML attribute

Question

I have a text file called branch.txt:

$ cat branch.txt DEMAND_NAME-CR-1234 DEMAND_NAME-CR-8970 

Using the above branch name, I have to find and replace some values using a sed command:

branch_name=`(cat /tmp/branch.txt)` sed -i "s/deploy_branch/$branch_name/g" /tmp/input.file 

When I run the sed command, I get an error like the one below:

sed: -e expression #1, char 35: unterminated `s' command 

Expected output:

<Project description="first-deployment" name="DEMAND_NAME-CR-1234 DEMAND_NAME-CR-8970 " overwrite="true" type="Repository"> </Project> 

Input file:

<Project description="first-deployment" name="deploy_branch" overwrite="true" type="Repository"> </Project> 

Answer 1

The issue with your sed command is that $branch_name contains an embedded newline character. This breaks the syntax of the substitution command in sed when you inject it into the sed editing expression.

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Using xmlstarlet to update the name attribute of the document's Project root node to be the contents of the branch.txt file with each newline replaced by a space:

xmlstarlet edit \ --update '/Project/@name' \ --value "$(paste -s -d ' ' branch.txt)" input.file 

or, shorter,

xmlstarlet ed \ -u '/Project/@name' \ -v "$(paste -s -d ' ' branch.txt)" input.file 

The paste command in the command substitution reads the branch.txt file and replaces each newline, apart from the last, with a space character. This results in a string used as the new value for the name attribute. If you want to retain the final newline character and convert it into a trailing space (as in your expected output), then use tr '\n' ' ' <branch.txt in place of the paste command.

The xmlstarlet utility is invoked with its ed sub-command. This command edits an XML file, and we specify that we'd like to update a particular element via an XPath query matching the attribute.

Would you need to make the change only when the name attribute's value is deploy_branch, then use the XPath query /Project/@name[. = "deploy_branch"] or /Project[@name = "deploy_branch"]/@name instead.

The output of the above commands would be

<?xml version="1.0"?> <Project description="first-deployment" name="DEMAND_NAME-CR-1234 DEMAND_NAME-CR-8970" overwrite="true" type="Repository"> </Project> 

The xmlstarlet tool can be made to make an in-place edit if you give it the --inplace (-L) option after ed or edit. You may avoid having the <?xml ...> declaration added by using --omit-decl (-O).