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pidof: allow to change a separator put between pids 

I frequency use pidof command with strace system call tracer.
strace can trace MULTIPLE processes specified with "-p $PID"
arguments like:

	  strace -p 1 -p 1030 -p 3043

Sometimes I want to do as following

	  strace -p $(pidof httpd)

However, above command line doesn't work because -p option
is needed for specifying a pid. pidof uses a whitespace as
a separator. For passing the output to strace, the separator
should be replaced with ' -p '.

This maybe not a special to my use case.

This commit introduces -S option that allows a user to specify a
separator the one wants.

    $ ./pidof bash
    ./pidof bash
    24624 18790 12786 11898 11546 10766 7654 5095
    $ ./pidof -S ',' bash
    ./pidof -S ',' bash
    24624,18790,12786,11898,11546,10766,7654,5095
    $ ./pidof -S '-p ' bash
    ./pidof -S '-p ' bash
    24624-p 18790-p 12786-p 11898-p 11546-p 10766-p 7654-p 5095
    $ ./pidof -S ' -p ' bash
    ./pidof -S ' -p ' bash
    24624 -p 18790 -p 12786 -p 11898 -p 11546 -p 10766 -p 7654 -p 5095
    $ strace -p $(./pidof -S ' -p ' bash)
    strace -p $(./pidof -S ' -p ' bash)
    strace: Process 24624 attached
    strace: Process 18790 attached
    strace: Process 12786 attached
    ...

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
This commit is contained in:
Masatake YAMATO 2018-02-24 18:03:11 +09:00 committed by Craig Small
parent 1ddd17b17c
commit 7f5971058a
2 changed files with 13 additions and 2 deletions
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5
pidof.1
View File

@ -27,6 +27,8 @@ pidof -- find the process ID of a running program.
.IR omitpid[,omitpid..] ]
.RB [ \-o
.IR omitpid[,omitpid..].. ]
.RB [ \-S
.IR separator ]
.B program
.RB [ program.. ]
.SH DESCRIPTION
@ -47,6 +49,9 @@ shells running the named scripts.
Tells \fIpidof\fP to omit processes with that process id. The special
pid \fB%PPID\fP can be used to name the parent process of the \fIpidof\fP
program, in other words the calling shell or shell script.
.IP "-S \fIseparator\fP"
Use \fIseparator\fP as a separator put between pids. Used only when
more than one pids are printed for the program.
.SH "EXIT STATUS"
.TP
.B 0

10
pidof.c
View File

@ -65,6 +65,7 @@ static int __attribute__ ((__noreturn__)) usage(int opt)
fputs(_(" -c, --check-root omit processes with different root\n"), fp);
fputs(_(" -x also find shells running the named scripts\n"), fp);
fputs(_(" -o, --omit-pid <PID,...> omit processes with PID\n"), fp);
fputs(_(" -S, --separator SEP use SEP as separator put between PIDs"), fp);
fputs(USAGE_SEPARATOR, fp);
fputs(USAGE_HELP, fp);
fputs(USAGE_VERSION, fp);
@ -290,12 +291,14 @@ int main (int argc, char **argv)
int found = 0;
int first_pid = 1;
const char *opts = "scnxmo:?Vh";
const char *separator = " ";
const char *opts = "scnxmo:S:?Vh";
static const struct option longopts[] = {
{"check-root", no_argument, NULL, 'c'},
{"single-shot", no_argument, NULL, 's'},
{"omit-pid", required_argument, NULL, 'o'},
{"separator", required_argument, NULL, 's'},
{"help", no_argument, NULL, 'h'},
{"version", no_argument, NULL, 'V'},
{NULL, 0, NULL, 0}
@ -327,6 +330,9 @@ int main (int argc, char **argv)
pidof_root = pid_link(getpid(), "root");
}
break;
case 'S':
separator = optarg;
break;
case 'V':
printf (PROCPS_NG_VERSION);
exit (EXIT_SUCCESS);
@ -360,7 +366,7 @@ int main (int argc, char **argv)
first_pid = 0;
printf ("%ld", (long) procs[i].pid);
} else {
printf (" %ld", (long) procs[i].pid);
printf ("%s%ld", separator, (long) procs[i].pid);
}
if (opt_single_shot) break;
}