CODEWITHSUNDEEP
bashsignals
Wakan Tanka
Wakan Tanka

Reputation: 8052

Handling multiple signals with one trap in bash

There is question about multiple bash traps for same signal. What about the opposite version? Is possible to write something like this:

sighand () {
  case $1 in
    1)
      echo "CATCH: SIGHUP"
      ;;
    2)
      echo "CATCH: SIGINIT"
      ;;

    ...
    # ALL EXCEPT 9
    ...

  esac
 };

 trap sighand ALL

instead of this:

sighand () {
  echo "CATCH: TERM"
};
trap sighand TERM

Upvotes: 3

Views: 5526

Answers (3)

Nathan S.R.
Nathan S.R.

Reputation: 47

Handling multiple signals with one trap in bash :

trap '' 2 3 6 15 18 20

Only Close Terminal Window will work in this case to Quit the Script.

This one liner is taken from my open source project called Automated_Quiz, which is hosted here : https://sourceforge.net/projects/automated-quiz/

Also check : https://www.computerhope.com/unix/signals.htm

Upvotes: 0

PhilipA
PhilipA

Reputation: 1

This answer should do it: Identifying received signal name in Bash. I've used it for a similar reason. A minor extention to @Leistungsabfall's above. This amendment adds the ability to specify a function to use in the trap by name. Example here:

trap_with_arg() {
    func="$1" ; shift
    for sig ; do
        trap "$func $sig" "$sig"
    done
}

function handler() {
  local SIGNAL=${1}
  [ "${DEBUG}" -gt "0" ] && echo "Received Signal: ${SIGNAL}" >&2

  case "${SIGNAL}" in
    EXIT)
      [ "${DEBUG}" -gt "0" ] && echo "EXIT clause"
      # ^C
      ;;
    USR2)
      [ "${DEBUG}" -gt "0" ] && echo "DUSR2 clause"
      ;;
    HUP|USR1)
      [ "${DEBUG}" -gt "0" ] && echo "HUP|USR1 clause"
      ;;
    ABRT)
      [ "${DEBUG}" -gt "0" ] && echo "ABRT clause"
      ;;
    INT|TERM)
      [ "${DEBUG}" -gt "0" ] && echo "INT|TERM clause"
      ;;
  esac
  exit 0
}

trap_with_arg handler USR1 USR2 HUP INT ABRT TERM EXIT

Upvotes: 0

baf
baf

Reputation: 4681

You would have to write separate function for each signal:

handle_hup () {
  echo "CATCH: SIGHUP";
}
handle_int () {
  echo "CATCH: INT";
}

trap handle_hup HUP
trap handle_int INT

As a workaround you could write a custom function to set all the traps for you. Then you would call the function with all the signals you want to be handled: _trap [sig1] [sig2] ...

handle_sig () {
  case "$1" in
    HUP)
      echo "CATCH: SIGHUP"
      ;;
    INT)
      echo "CATCH: SIGINT"
      ;;
    *)
      echo "CATCH: SIG$1"
      ;;
  esac
}

_trap () {
  for sig in "$@"
  do
    trap "handle_sig $sig" "$sig"
  done
}

_trap INT HUP USR1

Upvotes: 4

Related Questions