# Function to help manage traps
# Al Williams - Hackaday, August 2019
#
# Here's what it does:
# 1) Provide a function trappist_trap
# 2) Call trappist_init with or without arguments
#
# If you forget to provide trappist_trap, a stupid one will be provided but you can
# still override it later
# With no arguments to trappist_init, all signals you can catch go through your function with an argument indicating which signal fired
# You can ignore it or reraise it as shown in the default handler (see below)
# Of course, you can't do anything with signals you can't catch (e.g., kill -9)
#
# If you provide a list of signals that start with + or -, you will cause those signals to get the default handler (+) or
# to be ignored totally (-) assuming you are allowed to ignore the signal.
# Example:
# trappist_init +SIGQUIT -SIGHUP -SIGILL
#
# If you use the first argument as = you will ONLY catch the signals you name by themselves or with an = prefix and then
# you can also use the + and - prefix, although since + will be the default, you'll probably only need -
# Example:
# trappist_init = SIGQUIT SIGHUP
# trappist_init = =SIGQUIT =SIGHUP # same as above
# trappist_init = SIGQUIT -SIGHUP
#
# For regularity, you can use @ as the first argument to get the default behavior
# trappist_init @ +SIGQUIT -SIGHUP -SIGILL # same as earlier example without @ or =
#
# Normally, you should define your trappist_trap function and then source this file (. /path/to/trappist.sh)
# However, you can define trappist_trap afterwards
Example code:
# Really simple trap handler
function trappist_trap()
{
echo Trap: $1
}
# test harness
trappist_init
echo Trap me @ $$!
while true
do sleep 5 # Note: most signals won't happen until after sleep returns!
echo Still going
done