commit bash-20130301 snapshot

examples/scripts/timeout3

@@ -0,0 +1,92 @@
+#!/bin/bash
+#
+# The Bash script executes a command with a time-out.
+# Based on the Bash documentation example.
+#
+# Upon time-out expiration SIGTERM (15) is sent to the process.  If the signal
+# is blocked, then the subsequent SIGKILL (9) terminates it.
+# Dmitry V Golovashkin (E-mail: dvg@ieee.org)
+#
+script_name="${0##*/}"
+
+# Default values.
+readonly param_timeout=5
+readonly param_interval=1
+readonly param_delay=1
+
+declare -i timeout=param_timeout
+declare -i interval=param_interval
+declare -i delay=param_delay
+
+blue="$(tput setaf 4)"
+bold_red="$(tput bold; tput setaf 1)"
+off="$(tput sgr0)"
+
+function print_usage() {
+cat <<EOF
+
+Synopsis:  $script_name [-t timeout] [-i interval] [-d delay] command
+
+Executes the command with a time-out.  Upon time-out expiration SIGTERM (15) is
+sent to the process.  If SIGTERM signal is blocked, then the subsequent SIGKILL
+(9) terminates it.
+
+$blue-t timeout$off
+    Number of seconds to wait for command completion.
+    Default value: $param_timeout seconds.  In some practical situations
+    this value ${bold_red}must$off be increased (for instance -t 180) to allow
+    the command to complete.
+
+$blue-i interval$off
+    Interval between checks if the process is still alive.
+    Positive integer, default value: $param_interval seconds.
+    Default value is OK for most situations.
+
+$blue-d delay$off
+    Delay between posting the SIGTERM signal and destroying the process by
+    SIGKILL.  Default value: $param_delay seconds.
+    Default value is OK for most situations.
+
+As of today, Bash does not support floating point arithmetic (sleep does),
+therefore all time values must be integers.
+Dmitry Golovashkin (E-mail: dvg@ieee.org)
+EOF
+exit 1 # No useful work was done.
+}
+
+# Options.
+while getopts ":t:i:d:" option; do
+    case "$option" in
+        t) timeout=$OPTARG ;;
+        i) interval=$OPTARG ;;
+        d) delay=$OPTARG ;;
+        *) print_usage ;;
+    esac
+done
+shift $((OPTIND - 1))
+
+# $# should be at least 1 (the command to execute), however it may be strictly
+# greater than 1 if the command itself has options.
+if (($# == 0 || interval <= 0)); then
+    print_usage
+fi
+
+# kill -0 pid   Exit code indicates if a signal may be sent to "pid" process.
+(
+    ((t = timeout))
+
+    while ((t > 0)); do
+        sleep $interval
+        kill -0 $$ || exit 0
+        ((t -= interval))
+    done
+
+    # Be nice, post SIGTERM first.
+    # The 'exit 0' below will be executed if any preceeding command fails.
+    kill -s SIGTERM $$ && kill -0 $$ || exit 0
+    sleep $delay
+    kill -s SIGKILL $$
+) 2> /dev/null &
+
+exec "$@"
+