Re: trap problem on bash 4.2
On 3/21/11 8:46 AM, sky wrote: > Bash Version: 4.2 > Patch Level: 8 > Release Status: release > > Description: > I am a programmer working in Japan. > I encountered an incompatibility between bash 4.2 and 4.1. Thanks for the report. I made some changes in this area between bash-4.1 and bash-4.2 in response to a Posix interpretation: http://austingroupbugs.net/view.php?id=53 I think Posix is ambiguous about the disposition of signals that are ignored when a new shell or subshell is started, or at least open to differing interpretations -- ksh93 behaves as bash-4.2 does, for instance, where dash and mksh behave like bash-4.1 -- but I think it's better not to deliberately introduce an incompatibility. I will revert to the bash-4.1 behavior for the next release. This may or may not come out as a patch to bash-4.2. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
bizarre trap behavior while reading a file
I started execution of the following script and and repeatedly sent a SIGHUP
to it from another shell. If SIGHUP is received within the first while loop
the loop terminates with "wc -l" printing fewer than 4158 lines. If SIGHUP
is received within the second while loop the loop still continues and the
second "wc -l" prints always 4158 lines.
I am really curious why is this happening!!!
This is obviously a test scrip. I spent quite a long time debugging my work
script to get to this point ;).
#!/bin/bash
log_file=
line_num=0
trap "sig_received=true" HUP
rm out.log
cat $log_file | {
while read line
do
line_num=`expr $line_num + 1`
echo $line_num: $line >> ./out.log
done
}
wc -l out.log
rm out.log
line_num=0
while read line
do
line_num=`expr $line_num + 1`
echo $line_num: $line >> ./out.log
done < $log_file
wc -l out.log
exit 0
--
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Re: bizarre trap behavior while reading a file
On 3/25/11 5:25 PM, tytus64 wrote: > > I started execution of the following script and and repeatedly sent a SIGHUP > to it from another shell. If SIGHUP is received within the first while loop > the loop terminates with "wc -l" printing fewer than 4158 lines. If SIGHUP > is received within the second while loop the loop still continues and the > second "wc -l" prints always 4158 lines. > > I am really curious why is this happening!!! You don't say anything about what version of bash you're using or what OS you're on, but I couldn't reproduce it. I modified the script to print $$ at the beginning, so I knew which pid to hit, and hammered it with kill -HUP pid from another terminal. Each loop consumed and wrote 4158 lines. I tried it on both Mac OS X and RHEL 4 with the same results. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
