Perl CLI in-place string substitution/replacement of multiple lines with special characters

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I’m trying to write a CLI command to change the contents of a config file.

The config file has these lines:

JAVA_OPTS="$JAVA_OPTS -XX:+UseParNewGC"
JAVA_OPTS="$JAVA_OPTS -XX:+UseConcMarkSweepGC"

I want to change those two lines to this one line:

JAVA_OPTS="$JAVA_OPTS -XX:+UseG1GC"

I want to replace multiple lines, so I’m trying to use Perl to do that.

perl -i -pe 's/JAVA_OPTS="\$JAVA_OPTS -XX:\+UseParNewGC"\nJAVA_OPTS="\$JAVA_OPTS -XX:\+UseConcMarkSweepGC"/JAVA_OPTS="$JAVA_OPTS -XX:+UseG1GC"/' name-of-file.sh

However, this command doesn’t change the file. I’m guessing the regular expression doesn’t match. I don’t know why. I’ve tried several variations of the command and I’ve tried escaping and double-escaping the $ and + symbols in the match string, but nothing I do makes a difference. Can someone please offer a solution?

I’m using Bash 3.2.57(1) and Perl 5.18.4 on macOS.

perl replace regex
1 Answers

Try this perl command line with -0777 and \R instead of \n. -0777 enabled slurp mode in perl to match across multiple lines and \R lets it match all kind of line breaks (including DOS or OSX or Unix line breaks):

perl -0777 -i -pe 's/JAVA_OPTS="\$JAVA_OPTS -XX:\+UseParNewGC"\nJAVA_OPTS="\$JAVA_OPTS -XX:\+UseConcMarkSweepGC"/JAVA_OPTS="\$JAVA_OPTS -XX:+UseG1GC"/' file
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