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From: Roger <rogerx.oss@gmail.com>
Newsgroups: gnu.bash.bug
Subject: Protect Loop Execution with Traps
Date: Mon, 27 Jan 2020 21:03:22 -0500
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I've always had a problem with Bash script (eg. for/while) loops creating h=
avoc=20
upon a ctrl-c keypress.

One good idea, is not to put statements (eg. rm) within the loop that could=
=20
possibly create problems upon partial execution.

Another idea, addressing the monkey within the room, should a trap statemen=
t=20
always be used within for/while loops?

Or would a trap even help at all?

I've seen some examples on the Internet where a subshell, eg. "( statements=
 )",=20
is included within the loop, however this seems to cause more problems as a=
=20
value of a counter variable (i=3Di+1) cannot be easily incremented due to=
=20
subshells not inherienting previously defined variables of the parent shell.

Example Script:=20


#!/bin/bash

declare -i i=3D0

while (( $i >=3D 0 )); do
	# Protect loop
	trap "printf 'Caught SIGINT\n'; exit" SIGINT
   =20
    # Statements here
	printf "Pres CTRL+C to stop... %s\n" ${i}
	=09
	sleep 1
	=09
	let "i++"

done




--=20
Roger
http://rogerx.sdf.org/

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