Grep Matcher: wait to match first case and exit

Grep Matcher.md

grep_matcher.sh

#!/bin/bash
#
# grep matcher: wait to match first case and exit

grep_expression="$1"
grep_file="$2"
__matched=1

echo "### waiting... ###"

while [ "$__matched" == "1" ];
do
  grep "$grep_expression" "$grep_file";
  __matched=$?;
  sleep 0.2
done

echo '### matched!   ###'

Execution:

bash grep_matcher.sh "my custom string" /tmp/1.log

Output:

### waiting... ###
my custom string
### matched!   ###