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Top Forums Shell Programming and Scripting In ksh, how does an in-line child sub-process get its own PID? Post 302074761 by MichLab on Thursday 25th of May 2006 03:47:09 PM
Old 05-25-2006
Then how would the following ever work:
xxx=$(date)
( sleep 5
xxx=$(date)
echo $xxx
) &
echo $xxx
if $xxx were coerced when the (...)& is being scanned, then the two echo statements would always show the same time but they don't (you can try it). Are you suggesting that $$ is coerced by different rules than $xxx?
 

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PIDOF(8)						Linux System Administrator's Manual						  PIDOF(8)

NAME
pidof -- find the process ID of a running program. SYNOPSIS
pidof [-s] [-c] [-n] [-x] [-m] [-o omitpid[,omitpid..]] [-o omitpid[,omitpid..]..] program [program..] DESCRIPTION
Pidof finds the process id's (pids) of the named programs. It prints those id's on the standard output. This program is on some systems used in run-level change scripts, especially when the system has a System-V like rc structure. In that case these scripts are located in /etc/rc?.d, where ? is the runlevel. If the system has a start-stop-daemon (8) program that should be used instead. OPTIONS
-s Single shot - this instructs the program to only return one pid. -c Only return process ids that are running with the same root directory. This option is ignored for non-root users, as they will be unable to check the current root directory of processes they do not own. -n Avoid stat(2) system function call on all binaries which are located on network based file systems like NFS. Instead of using this option the the variable PIDOF_NETFS may be set and exported. -x Scripts too - this causes the program to also return process id's of shells running the named scripts. -o omitpid Tells pidof to omit processes with that process id. The special pid %PPID can be used to name the parent process of the pidof pro- gram, in other words the calling shell or shell script. -m When used with -o, will also omit any processes that have the same argv[0] and argv[1] as any explicitly omitted process ids. This can be used to avoid multiple shell scripts concurrently calling pidof returning each other's pids. EXIT STATUS
0 At least one program was found with the requested name. 1 No program was found with the requested name. NOTES
pidof is actually the same program as killall5; the program behaves according to the name under which it is called. When pidof is invoked with a full pathname to the program it should find the pid of, it is reasonably safe. Otherwise it is possible that it returns pids of running programs that happen to have the same name as the program you're after but are actually other programs. Note that that the executable name of running processes is calculated with readlink(2), so symbolic links to executables will also match. SEE ALSO
shutdown(8), init(8), halt(8), reboot(8), killall5(8) AUTHOR
Miquel van Smoorenburg, miquels@cistron.nl 01 Sep 1998 PIDOF(8)
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