I need to use command that shows all processes related to terminal. Ps -a looks good except that there is no username printed. This command prints:
PID TTY TIME CMD
26969 pts/34 0:00 man
27636 pts/2 0:00 awk
25215 pts/35 0:00 bash
I would like it to be similar to this:
PID TTY TIME CMD USER
26969 pts/34 0:00 man name
27636 pts/2 0:00 awk name
25215 pts/35 0:00 bash name
Columns order does not matter
Use:
ps a -o pid,tty,etime,cmd,user
From ps manual:
SIMPLE PROCESS SELECTION
a ... An alternate description is that this option causes ps to list all processes with a terminal (tty), or to list all processes
when used together with the x option.
STANDARD FORMAT SPECIFIERS
Here are the different keywords that may be used to control the output format (e.g. with option -o) or to sort the selected processes
with the GNU-style --sort
option.
For example: ps -eo pid,user,args --sort user
I have found that ps -af works the way I want
Related
I meant to use the following command to grep the "zsh" process with header. But this command only showed the header and then exited. The grep didn't run. I can do this task by other ways but I want to understand what happened here. The interesting thing is that the pipe works as expected if other command like ls replaces ps -e. In fact, the pipe works even with ps (without -e). The pipe also works if head is replaced by another grep. Seemingly, there are some interesting interactions between ps -e, head and tee in this pipe. Any explanation? I ran the commands in MacOS-iterm2 and zsh. Thanks.
ps -e|tee >(head -n 1) >(grep "zsh") >/dev/null
the command above produces the following incorrect output: only header is shown, grep didn't run.
PID TTY TIME CMD
The correct output can be generated by the following command:
ps -e|awk 'FNR==1{print};/zsh/{print}'
PID TTY TIME CMD
1658 ttys000 0:00.30 -zsh
2817 ttys001 0:00.49 /bin/zsh -i
12890 ttys002 0:00.26 -zsh
13332 ttys003 0:00.23 -zsh
13469 ttys004 0:00.19 /bin/zsh -i
Update: The problem is indeed in the tee shipped with MacOS. As #OndrejK. pointed out in the comments below, tee from GNU works as expected.
I think Ondrej K. nailed it in a comment: head is reading just the first line it receives from tee, then exiting, so when tee tries to write the second line to that pipe, it gets an error (probably actually a SIGPIPE signal) and exits without writing the rest of ps's output.
I was able to reproduce this problem under both macOS and Raspbian, using both zsh and bash as my shell. I was able to get the full output by replacing head with something that reads (but doesn't output) the rest of the input from tee. Here's an example:
% ps -e|tee >(head -n 1) >(grep "zsh") >/dev/null
PID TTY TIME CMD
% ps -e|tee >(head -n 1; cat>/dev/null) >(grep "zsh") >/dev/null
PID TTY TIME CMD
13127 pts/0 00:00:00 zsh
13353 pts/0 00:00:00 zsh
% ps -e|tee >(sed -n '1p') >(grep "zsh") >/dev/null
PID TTY TIME CMD
13127 pts/0 00:00:00 zsh
In the second version above, adding cat>/dev/null after head lets it consume (and discard) the rest of the input after head exits. In the third, sed -n '1p' reads its entire input, but only prints the first line.
Note that the result here will depend on things like buffer sizes and the timing of various events, so it may be inconsistent between different environments or even vary randomly under apparently consistent conditions. I suspect the reason it works with ps (without the -e option) is that it doesn't produce enough output to trigger the problem: tee may be able to forward the entire output from ps before head gets around to exiting.
EDIT: At least in my environments, adding a delay after head exits prevents the problem:
% ps -e|tee >(head -n 1; sleep 1) >(grep "zsh") >/dev/null
PID TTY TIME CMD
8002 pts/0 00:00:00 zsh
8164 pts/0 00:00:00 zsh
This means it's timing-limited, rather than buffer-limited. But if the output from ps were big enough, it'd run into buffer limits at some point, and the output would be truncated no matter what delays were inserted.
I have an executable file that contains a long loop, so I want to run it in background, how do I do that with bash script in Linux?
I know one way is Ctrl + z, then I type bg, how to simulate these key pressing in bash script?
Any executable in linux can be run in the background as follows:
$ ./yourExecutable.exe&
Add the & character at end. (Assuming yourExecutable.exe is in the current working directory)
How to kill it later on?
$ ps -ax | grep yourExecutable.exe
You will get an output like:
9384 pts/7 S+ 0:00 grep yourExecutable.exe
25082 pts/7 T 0:00 yourExecutable.exe&
Kill the second process using SIGKILL. That is the one you executed in the background.
$ kill -9 25082
I want to get the PID of a process namely "cron" by command line.
I tried the following script.
ps ax|grep 'cron'
but I am getting a part of a table,
1427 ? Ss 0:00 /usr/sbin/cron -f
24160 pts/5 S+ 0:00 grep --color=auto cron
How I extract the pid from this ?
The pgrep utility will return the process IDs for the currently running processes matching its argument:
$ pgrep cron
228
It may also be used to "grep for" things on the command line:
$ pgrep -f uerfale
69749
69752
$ pgrep -l -f uerfale
69749 slogin uerfale
69752 slogin: /home/kk/.ssh/sockets/uerfale-9022-kk.sock [mux] m
To kill a process by name, use pkill. It works in the same way as pgrep but will send a signal to the matched processes instead of outputting a process ID.
Just use pidof, rather to use other commands and apply post-processing actions on them.
$ pidof cron
22434
To make the command return only one PID pertaining to to the process, use the -s flag
-s
Single shot - this instructs the program to only return one pid.
Like this, for example:
ps -ef|grep 'cron'|grep -v grep|awk '{print $2}'
You can try this;
ps -o pid,sess,cmd afx | egrep "( |/)cron( -f)?$"
or
pstree -pas <cronPID>
I'm running two levels of xterms. In the first level I run "xterm -e bsub -Ip master.tcl". The master.tcl script invokes yet another xterm with "xterm -e bsub -Ip slave.tcl".
From some reason, when slave.tcl finishes executing, the second xterm is not closing. However, the second xterm does display the following message once the slave script finishes:
<< JobExitInfo: Job <128309> is done successfully. >>
Also, when looking at the LSF system, the job does not appear, as if it really finished. But the xterm window stays open, instead of closing.
Any idea why?
Thanks.
It is unlikely that xterm would stay open unless there was something still running there.
I'd check (using ps -ef for instance) to see what processes are still running in the remaining xterm. xterm would only be still open if there were something running, e.g., waiting for input.
Using ps -ef (assuming this is not a BSD system), you would see a listing with a heading like this:
UID PID PPID C STIME TTY TIME CMD
and later in the listing, the relevant information, e.g.,
tom 3647 20185 0 06:17 pts/2 00:00:00 sh -c xterm -e vile
tom 3648 3647 0 06:17 pts/2 00:00:00 xterm -e vile
tom 3649 3648 0 06:17 pts/3 00:00:00 vile
tom 3650 3649 0 06:17 pts/3 00:00:00 sh -c ps -ef
tom 3651 3650 0 06:17 pts/3 00:00:00 ps -ef
xterm's process-id (PID) is the place to start. It would be found in the PPID (parent's process-ID) column at least one other place. In turn, that process's PID may be used in further child-processes.
BSD systems use a different set of options (see FreeBSD for example), but in general you can obtain the necessary information from ps.
I was trying to write a set of functions that could check to see if a process name was running when I encountered some unexpected output. I've condensed the issue in the following script names isRunning.sh which depends on a system ps command that can take the '-fC' arguments...
#!/bin/bash
progname=isRunning.sh
ps -fC isRunning.sh
pRet=`ps -fC ${progname} | wc -l`
echo pRet $pRet
psOut=`ps -fC ${progname}`
wcOut=`echo "${psOut}" | wc -l`
echo
echo ps output
echo "${psOut}"
echo
echo wcOut $wcOut
The first attempt at piping the ps output to wc gets a return of 3. The second attempt gets the expected return value of 2. Can anyone explain this behavior? I figure it's got to be something stupid I am overlooking.
Thanks,
bbb
edit: my output
UID PID PPID C STIME TTY TIME CMD
root 6717 5940 0 13:10 pts/0 00:00:00 /bin/bash ./isRunning.sh
pRet 3
ps output
UID PID PPID C STIME TTY TIME CMD
root 6717 5940 0 13:10 pts/0 00:00:00 /bin/bash ./isRunning.sh
wcOut 2
I get 2 both attempts. Your ps might be outputting an extra blank line, or somesuch, and then your shell's backtick expansion stripping it. Or maybe you actually had two processes matching the first time you ran it.
If you just want to see if its running, check the exit code from your ps:
if ps -C "${progname}" > /dev/null; then
echo its running
else
echo not running
fi
Even better, you should take a look at pidof and pgrep if you can rely on them being present on whichever systems you're targeting. Or use the LSB functions, if you're on Linux.
edit: Actually, since you're looking for copies of yourself running, you might be picking up the shell doing a fork to implement the pipe.