Tail file till process exits

Question

Going through the answers at superuser .

I'm trying to modify this to listen for multiple strings and echo custom messages such as ; 'Your server started successfully' etc

I'm also trying to tack it to another command ie pip

wait_str() {
  local file="$1"; shift
  local search_term="Successfully installed"; shift
  local search_term2='Exception'
  local wait_time="${1:-5m}"; shift # 5 minutes as default timeout

  (timeout $wait_time tail -F -n0 "$file" &) | grep -q "$search_term" && echo 'Custom success message' && return 0 || || grep -q "$search_term2" && echo 'Custom success message' && return 0

  echo "Timeout of $wait_time reached. Unable to find '$search_term' or '$search_term2' in '$file'"
  return 1
}

The usage I have in mind is:

pip install -r requirements.txt > /var/log/pip/dump.log && wait_str /var/log/pip/dump.log

To clarify, I'd like to get wait_str to stop tailing when pip exits, whether successfully or not.

Answer 1

Following is general answer and tail could be replaced by any command that result in stream of lines.

IF different string needs different actions then use following:

tail -f var/log/pip/dump.log |awk '/condition1/ {action for condition-1} /condition-2/ {action for condition-2} .....' 

If multiple conditions need same action them ,separate them using OR operator :

tail -f var/log/pip/dump.log |awk '/condition-1/ || /condition-2/ || /condition-n/ {take this action}'

Based on comments : Single awk can do this.

tail -f /path/to/file |awk '/Exception/{ print "Worked"} /compiler/{ print "worked"}'  

or

tail -f /path/to/file | awk '/Exception/||/compiler/{ print "worked"}' 

OR Exit if match is found

tail -f logfile |awk '/Exception/||/compiler/{ print "worked";exit}'