[ILUG] bash bug?

[Brian Foster]

  | Date: Fri, 14 Jun 2002 12:12:14 +0100
  | From: Stephen Shirley <diamond at skynet.ie>
  |
  | [ ... The bash script is ] supposed to allow ctrl-c to be pressed during
  | the sleep_60 function, which should just return, and all it well.
  | However, it only works the first time.  The next time sleep_60 is called
  | [ the trap does not appear to be taken ... ].
  | 
  | So, can anyone see any problems [ ... ] or is it actually a bash bug (or
  | even something else)?

 interesting.  at first glance, and sans googling, it does
 sort of look like a bash(1) problem ....

 fix (work-around) is trivial (tested with bash 2.05.0(1)
 on SuSE 7.3; but may _not_ work other Bourne-ish shells,
 due to various syntax issues such as the `local' builtin
 and `return -1'):

=====(cut here and below)=====(working variant of original)=====(bash script)=====
#!/bin/bash

function sleep_60 {
    local i=60
    trap 'i=-1' INT
    echo -n "Died ... restarting in "
    while [ $i -gt 0 ]; do
        echo -n "$i"
        i=$((i-1))
        sleep 1
        echo -n ' '
    done
    echo NOW
	# unlike ksh(1), bash(1) traps are global, so be sure to clean up in
	# _all_ cases (i.e., whether or not the trap is taken) --- otherwise
	# there will be a lurking reassignment of `i' on any subsequent INT
	# (almost certainly not what is wanted!) ...
	#
	# N.b. following resets the INT handler to the original value when
	#      the script started, which is not always what's wanted  ;-(
	#
    trap - INT
    return $i
}

while true; do
    #... do stuff
    sleep_60
done
=====(cut here and above)=====(working variant of original)=====(bash script)=====

 the comment within the above work-around also points out
 a problem in the original script --- it left the `return'
 handler active for any SIGINT (e.g., ctrl-C) subsequent to
 the first invocation of sleep_60, which is very unlikely
 to be desired!

cheers,
	-blf-
--
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