Some SED questions.

Need some Linux grep & sed help

I need to read a file and search for a specific string. It the string does not exist I want to add it to the end of the file, if it does exist I want to replace the whole line I think I can do this all with a BASH script but don't exactly know how.

Here is my example:

Code:

if grep -q 'firmwareupdater:' config.yaml
then
  sed -i 's/avrdud_path:\(.*\)/avrdude_path: /usr/bin/avrdude/g config.yaml
else
  cat config.yaml
firmwareupdater:
  avrdude_path: /usr/bin/avrdude
EOF
fi

 

Just figured this out, the above code was just stupid and didn't work, but his code does.

Code:

#! /bin/bash

if grep -Fq 'firmwareupdater:' config.yaml
then
  sed -i 's|avrdud_path:.*|avrdude_path: /usr/bin/avrdude|g' config.yaml
  echo "line changed"
else
  cat <<EOT >> config.yaml
firmwareupdater:
  avrdude_path: /usr/bin/avrdude
EOT
  echo "Lines added"
fi