What is the meaning of this command, what does it do?
ps -aef | grep `pwd`
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From the man page for ps:
-a Select all processes except both session leaders (see getsid(2)) and processes not associated with a terminal. -f Do full-format listing. This option can be combined with many other UNIX-style options to add additional columns. It also causes the command arguments to be printed. When used with -L, the NLWP (number of threads) and LWP (thread ID) columns will be added. See the c option, the format keyword args, and the format keyword comm. -e Select all processes. Identical to -A.
grep is used to
print lines matching a pattern.
What it does
ps -aef | grep `pwd`
prints out all the lines matching the output of the command
pwd(which will be the path your current working directory), from the output of
saji@geeklap:~$ pwd /home/saji saji@geeklap:~$ ps -aef | grep `pwd` saji 2854 2814 0 09:51 ? 00:00:00 /usr/bin/ssh-agent /usr/bin/gpg-agent --daemon --sh --write-env-file=/home/saji/.gnupg/gpg-agent-info-geeklap /usr/bin/dbus-launch --exit-with-session gnome-session --session=ubuntu saji 2855 2814 0 09:51 ? 00:00:00 /usr/bin/gpg-agent --daemon --sh --write-env-file=/home/saji/.gnupg/gpg-agent-info-geeklap /usr/bin/dbus-launch --exit-with-session gnome-session --session=ubuntu saji 2879 1 0 09:51 ? 00:00:00 /usr/lib/gvfs//gvfs-fuse-daemon -f /home/saji/.gvfs saji 14242 14148 0 15:26 pts/7 00:00:00 grep --color=auto /home/saji
As you can see the output shows the lines matching my current working directory, which is
If a command is in $(...) or
..., then the command is run and the output (what is printed to the screen) is caught and substituted to where the original $() or `` string was. So the actual command run is grep pwd.
Do check out the following link for a detailed technical answer from the man pages itself:
ps: Displays information about a selection of the active processes.
ps -e for displaying all current working background processes
I cant understand what is -aef here
grep: Is for searching that specific work within process.
pwd: Print working directory .
I don't think its an useful and meaningful command. May I know for what purpose you are using it.