xinyou yan wrote: > thank you ! > > As you write . It works . > I thought it was captured by shell. In fact the error in cods. > I am just a student . > Someone told me some skills are import . However , I study it and > find I can't use it right now . > That lead careless . > > May be we need to find interest in programming . > Sounds as if you have mastered: - ask a decent question - listen to the answer - understand what you were told You have a good start, keep going. > > > 2011/3/7 Cameron Simpson<cs@xxxxxxxxxx>: >> On 07Mar2011 10:17, xinyou yan<yxy.716@xxxxxxxxx> wrote: >> | I want to know when i use >> | >> | trap 'rm -f /tmp/my_tmp_file_$$' INT >> | >> | why shell itself capture the single and she shellscript exit. >> >> But it doesn't! >> >> The shell captures the signal, runs the rm command, and proceeds. >> >> | Here is the code from<< Beginning Programming>> >> | #!/bin/sh >> | trap 'rm -f /tmp/my_tmp_file_$$' INT >> | echo creating file /tmp/my_tmp_file_$$ >> | date> /tmp/my_tmp_file_$$ >> | >> | echo "Press interrupt (Ctrl-C) to interrupt...." >> | while [ -f /tmp/my_tmp_file_$$ ]; do >> | echo File exists >> | sleep 1 >> | done >> | echo The file no longer exists >> >> When I run this script, this all works just fine. >> >> | trap INT >> >> However, _this_ line above is incorrect. >> "trap" requires a shell command to run, even if it is empty. >> For example: >> >> trap 'echo INT received' INT >> >> > From "man sh": >> >> trap [-lp] [[arg] sigspec ...] >> The command arg is to be read and executed when the shell >> receives signal(s) sigspec. [...snip...] If arg is the null >> string the signal specified by each sigspec is ignored by the shell >> and by the commands it invokes. [...snip...] >> >> When I run the script it aborts at that line. >> >> Try changing that line to: >> >> trap 'echo INT received' INT >> >> and rerunning your script. >> >> Cheers, >> -- >> Cameron Simpson<cs@xxxxxxxxxx> DoD#743 >> http://www.cskk.ezoshosting.com/cs/ >> >> More computing sins have been committed in the name of performance, >> without necessariliy achieving it, than for all other reasons >> combined. - Wulf >> -- >> users mailing list >> users@xxxxxxxxxxxxxxxxxxxxxxx >> To unsubscribe or change subscription options: >> https://admin.fedoraproject.org/mailman/listinfo/users >> Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines >> -- Bill Davidsen <davidsen@xxxxxxx> "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
