[Crash-utility] [PATCH] cmdline: allow to specify a script directly in pipeline

[Dave Anderson]

----- Original Message -----
> 
> 
> ----- Original Message -----
> > 
> > On 9/27/2018 1:42 PM, Dave Anderson wrote:
> > > 
> > > 
> > > ----- Original Message -----
> > >> Currently, when using pipe in command line, we cannot specify
> > >> a script with shebang directly like this:
> > >>
> > >>   crash> foreach bt | ./analyze.awk
> > >>   crash: pipe operation failed
> > >>
> > >>   (or it looks like crash can loop until Ctrl-C depending on timing)
> > >>
> > >> This is a bit confusing and inconvenient because it's not shell-like
> > >> behavior.
> > >>
> > >> The cause is that output_command_to_pids() searches /proc/PID/stat
> > >> files for "(path/to/script)" string and cannot find such process,
> > >> and also the ps kludge doesn't work well in this case.  This patch
> > >> removes the part except its file name like "(script)" so that it can
> > >> find the process.
> > > 
> > > Just to clarify, is this is due to using "./analyze.awk" (with the preceding "./"),
> > > whereas if you were to use "analyze.awk", it would work OK?
> > 
> > No, it doesn't because "sh -c analyze.awk" does not work.
> > This behavior will not change with this patch, and I think
> > it should not change.
> > 
> > [before]
> >   crash> bt | awk -f analyze.awk
> >   analyzed
> >   crash> bt | ./analyze.awk
> >   crash: pipe operation failed
> >   crash> bt | analyze.awk
> >   sh: analyze.awk: command not found
> >   crash: pipe operation failed
> > 
> > [after]
> >   crash> bt | awk -f analyze.awk
> >   analyzed
> >   crash> bt | ./analyze.awk
> >   analyzed
> >   crash> bt | analyze.awk
> >   sh: analyze.awk: command not found
> >   crash: pipe operation failed
> > 
> > Thanks,
> > Kazu
> 
> OK, it appears that if the output script (with #!) is specified beginning
> with either "./" or "/" it would fail.  (and works OK with the patch)

Kazu,

Your patch is queued for crash-7.2.5:

  https://github.com/crash-utility/crash/commit/ac8738376facd2d6de91ed62d29b6b654468ecf1

Thanks,
  Dave


> > >>
> > >> Signed-off-by: Kazuhito Hagio <k-hagio at ab.jp.nec.com>
> > >> ---
> > >>  cmdline.c | 5 +++--
> > >>  1 file changed, 3 insertions(+), 2 deletions(-)
> > >>
> > >> diff --git a/cmdline.c b/cmdline.c
> > >> index ee08f06..c0a9f4f 100644
> > >> --- a/cmdline.c
> > >> +++ b/cmdline.c
> > >> @@ -806,7 +806,7 @@ output_command_to_pids(void)
> > >>          char buf1[BUFSIZE];
> > >>          char buf2[BUFSIZE];
> > >>          char lookfor[BUFSIZE+2];
> > >> -        char *pid, *name, *status, *p_pid, *pgrp;
> > >> +        char *pid, *name, *status, *p_pid, *pgrp, *comm;
> > >>  	char *arglist[MAXARGS];
> > >>  	int argc;
> > >>  	FILE *pipe;
> > >> @@ -815,7 +815,8 @@ output_command_to_pids(void)
> > >>  	retries = 0;
> > >>  	shell_has_exited = FALSE;
> > >>  	pc->pipe_pid = pc->pipe_shell_pid = 0;
> > >> -        sprintf(lookfor, "(%s)", pc->pipe_command);
> > >> +	comm = strrchr(pc->pipe_command, '/');
> > >> +	sprintf(lookfor, "(%s)", comm ? ++comm : pc->pipe_command);
> > >>  	stall(1000);
> > >>  retry:
> > >>          if (is_directory("/proc") && (dirp = opendir("/proc"))) {
> > >> --
> > >> 1.8.3.1
> > >>
> > >> --
> > >> Crash-utility mailing list
> > >> Crash-utility at redhat.com
> > >> https://www.redhat.com/mailman/listinfo/crash-utility
> > >>
> > > 
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> > > 
> > 
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