| 1 | #!/bin/sh
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| 2 | #
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| 3 | # Show signal state in a shell
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| 4 | #
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| 5 | # Copied from:
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| 6 | # https://unix.stackexchange.com/questions/85364/how-can-i-check-what-signals-a-process-is-listening-to
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| 7 | #
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| 8 | # Usage:
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| 9 | # ./signal-report.sh <function name>
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| 10 |
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| 11 | set -o nounset
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| 12 | set -o errexit
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| 13 | #set -o pipefail
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| 14 |
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| 15 | sigparse() {
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| 16 | # Parse signal format in /proc.
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| 17 | local hex_mask=$1
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| 18 |
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| 19 | local i=0
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| 20 |
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| 21 | # bits="$(printf "16i 2o %X p" "0x$1" | dc)" # variant for busybox
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| 22 |
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| 23 | # hex to binary. Could also do this with Python.
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| 24 | bits="$(printf 'ibase=16; obase=2; %X\n' "0x$hex_mask" | bc)"
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| 25 | while test -n "$bits"; do
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| 26 | i=$((i + 1))
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| 27 | case "$bits" in
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| 28 | *1)
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| 29 | local sig_name=$(kill -l "$i")
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| 30 | printf ' %s(%s)' "$sig_name" "$i"
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| 31 | ;;
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| 32 | esac
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| 33 | bits="${bits%?}"
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| 34 | done
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| 35 | }
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| 36 |
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| 37 | report() {
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| 38 | local do_trap=${1:-}
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| 39 |
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| 40 | local pid=$$
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| 41 | echo "PID $pid"
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| 42 |
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| 43 | if test -n "$do_trap"; then
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| 44 | case "$do_trap" in
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| 45 | # Demo for blog post: trap ' ' is different than trap '' !
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| 46 | SPACE)
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| 47 | trap ' ' USR2
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| 48 | ;;
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| 49 | # trap '# comment' is also different than trap ''
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| 50 | COMMENT)
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| 51 | trap '# comment' USR2
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| 52 | ;;
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| 53 | *)
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| 54 | # trap '' sets SIG_IGN
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| 55 | trap '' USR2
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| 56 | #echo ' Ignoring USR2'
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| 57 | ;;
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| 58 | esac
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| 59 |
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| 60 | # Print trap state
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| 61 | trap
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| 62 | echo
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| 63 | fi
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| 64 |
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| 65 |
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| 66 | if false; then
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| 67 | # raw
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| 68 | grep '^SigIgn:' "/proc/$pid/status"
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| 69 | else
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| 70 | grep '^Sig...:' "/proc/$pid/status" | while read state hex_mask; do
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| 71 | printf "%s%s\n" "$state" "$(sigparse "$hex_mask")"
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| 72 | done
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| 73 | fi
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| 74 | }
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| 75 |
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| 76 | "$@"
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