Re: reset a trap upon use

[Greg Wooledge]

On Fri, Nov 24, 2023 at 11:08:03AM -0500, bill-auger wrote:
> #!/bin/bash
> 
> if i reset a trap within a helper function, or in a function called by the 
> trap,
> the trap is not reset
> 
> setup()   { echo "setup()"  ; trap 'cleanup' INT TERM RETURN ; helper ; 
> cleanup ; }
> helper()  { echo "helper()" ; }
> cleanup() { echo "cleanup() caller=${FUNCNAME[1]}" ; trap - INT TERM RETURN ; 
> }
> main()    { echo "main()"   ; setup ; helper ; }

I wonder what you're actually trying to do.  Bash (but not sh in general)
allows you to set an EXIT trap which is perfectly suited for running a
cleanup function when the scripts exits, either normally or due to a
fatal signal.

#!/bin/bash
cleanup() {
    rm stuff etc.
}
trap cleanup EXIT

Anything more complex than this is likely to fail in subtle ways due
to race conditions.  Using an EXIT trap instead of a SIGINT trap also
lets the script exit properly upon receipt of SIGINT, avoiding many of
the issues documented at <http://www.cons.org/cracauer/sigint.html>.

Did you actually need anything more than a cleanup-on-exit function?