What is the meaning of "ps -aef | grep $(pwd)" command?
What is the meaning of this command, what does it do?
ps -aef | grep `pwd`3 Answers
From the man page for ps:
-a Select all processes except both session leaders (see getsid(2)) and processes not associated with a terminal. -f Do full-format listing. This option can be combined with many other UNIX-style options to add additional columns. It also causes the command arguments to be printed. When used with -L, the NLWP (number of threads) and LWP (thread ID) columns will be added. See the c option, the format keyword args, and the format keyword comm. -e Select all processes. Identical to -A.grep is used to print lines matching a pattern.
What it does
The command
ps -aef | grep `pwd`prints out all the lines matching the output of the command pwd(which will be the path your current working directory), from the output of ps -aef.
e.g:
saji@geeklap:~$ 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/sajiAs you can see the output shows the lines matching my current working directory, which is /home/saji.
Background info:
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.
For more information refer this link.(Thanks to @minerz029 for this information).
Do check out the following link for a detailed technical answer from the man pages itself:
2ps -aef | grep $(pwd)Searching,Getting and displaying full information about the list of processes which are associated with the working directory and print the path of that directory.
ps: Displays information about a selection of the active processes.
like 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.
