Processes & Jobs

Job Control

more /etc/passwd  # don't page through the file; stay on the first screen
Ctrl+z  # this will suspend more and return to the shell
less /etc/fstab  # again don't page through the file
Ctrl+z  # suspend less
most /etc/services  # again don't page through the file
Ctrl+z  # suspend pg
ps  # shows your processes with Process IDs
jobs  # shows background jobs with status and job numbers
      # + indicates current job, - indicates previous job
fg  # this will bring the current job [3] to the foreground
Ctrl+z  # suspended it again
fg 2  # this will bring job [2] to the foreground (%2 also works)
Ctrl+z  # suspended it again
%1  # this will bring job [1] to the foreground
Ctrl+z  # suspended it again
%pg  # this will show the job named pg
Enter  # bring it to the foreground
Ctrl+z  # suspended it again

Processes

# open another terminal window, connect, and login again
tty  # this will show the name of the tty (terminal) for this session
ps  # this will show your processes in the current session
ps ax  # shows all processes (BSD options without -)
ps U $USER  # shows all processes of a specified user (BSD)
ps u  # user listing format (BSD)
ps l  # long listing format (BSD)
ps -e  # shows every process (UNIX options use -)
ps -f  # full format (UNIX)
ps -u $USER  # shows all processes of a specified user (UNIX)

Signals

kill -l   # (lowercase L) list available signals
ps -u $USER  # remember the PID (number) of pg
kill -9 PID  # (PID is the number above)
ps -u $USER  # you have killed pg in the other session
jobs  # this will only show jobs in the current shell (none)

Process Filesystem (Linux, deprecated in FreeBSD)

ls -F /proc  # filesystem interface to kernel data, numbered entries for processes
ps  # remember the PID (number) of your bash process
ls -F /proc/PID  # (PID is the number above) info for your bash process
cat /proc/sys/kernel/pid_max  # max PID, FreeBSD equivalent sysctl kern.maxproc

Background

# click in the other terminal window
delay.tcl 120 &  # tcl script (not part of UNIX) which waits for 120 seconds
                 # & will put delay.tcl in the background
jobs
fg
Ctrl+c  # terminate delay.tcl

Other Terminal

tty
ps -u $USER  # remember the PID (number) of the other shell (on the other tty)
kill -9 PID  # (PID is the number above) send kill signal to shell in other session
ps -u $USER  # you're logged out of other session

Nohup

nohup delay.tcl 300 &  # runs TCL script in the background even after logout
ps -u $USER
logout  # gives error message if you have stopped jobs
logout  # repeating the command will log you out anyway
# login again
jobs  # the new shell has no background jobs
ps -u $USER  # delay.tcl still running, remember its PID
kill -9 PID  # (PID is the number above)
ps -u $USER  # delay.tcl is gone

Related Commands

pstree: show processes as a tree
top: interactive processes display
killall: sends signals to process names rather than to process IDs
pkill, pgrep: combine functions of ps, grep, kill to search for processes and send signals