Different ways to keep a process running even after ssh logout or session/terminal is closed in linux ?
In this article, we will look at different ways to let our process running in background even after we close our terminal, or our session timeout, or due to any network connectivity issues.
This tip will help you to run the processes in background and keep them running even if your session is terminated due to any issue(s).
1. nohup and &
[root@nglinux ~]# nohup iostat -c 5 &
[1] 4498
[root@nglinux ~]# nohup: ignoring input and appending output to `nohup.out'
[root@nglinux ~]# ps -ef | grep -i iostat
root 4498 4176 0 23:19 pts/1 00:00:00 iostat -c 5
root 4502 4176 0 23:19 pts/1 00:00:00 grep -i iostat
[root@nglinux ~]# cat nohup.out
top: failed tty get
top: failed tty get
Linux 2.6.32-754.el6.i686 (nglinux) 04/23/2019 _i686_ (1 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
0.06 0.00 0.07 2.07 0.00 97.81
Linux 2.6.32-754.el6.i686 (nglinux) 04/23/2019 _i686_ (1 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
0.06 0.00 0.07 2.06 0.00 97.81
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.00 0.00 0.00 100.00
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.20 1.20 0.00 98.60
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.00 0.40 0.00 99.60
[root@nglinux ~]#
2. disown command
It runs the command in background, however the command is killed when session is terminated/closed.
[root@nglinux ~]# top & [1] 4755 [root@nglinux ~]# [1]+ Stopped top [root@nglinux ~]# disown -h %1 [root@nglinux ~]# [root@nglinux ~]# ps -ef | grep -i top root 5 2 0 18:21 ? 00:00:00 [stopper/0] root 4755 4390 0 23:37 pts/2 00:00:00 top root 4760 4390 0 23:37 pts/2 00:00:00 grep -i top
3. Setsid Command
Setsid runs in background, gets killed once session is terminated/closed.
[root@nglinux ~]# setsid iostat -c 5
[root@nglinux ~]# Linux 2.6.32-754.el6.i686 (nglinux) 04/23/2019 _i686_ (1 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
0.06 0.00 0.07 1.93 0.00 97.94
[root@nglinux ~]# ps -ef | grep -i avg-cpu: %user %nice %system %iowait %steal %idle
0.20 0.00 0.00 0.00 0.00 99.80
[root@nglinux ~]# ps -ef | grep -i iostat
root 4959 1 0 23:44 ? 00:00:00 iostat -c 5
root 4965 4918 0 23:44 pts/1 00:00:00 grep -i iostat
[root@nglinux ~]# avg-cpu: %user %nice %system %iowait %steal %idle
4. Screen Command
ngelinux:~ saket$ screen bash-3.2$ top Processes: 391 total, 4 running, 387 sleeping, 1603 threads 00:43:39 Load Avg: 1.83, 1.86, 1.79 CPU usage: 7.67% user, 15.34% sys, 76.97% idle SharedLibs: 208M resident, 47M data, 59M linkedit. MemRegions: 81093 total, 2553M resident, 67M private, 720M shared. PhysMem: 8109M used (1791M wired), 82M unused. VM: 1716G vsize, 1089M framework vsize, 3646(0) swapins, 4414(0) swapouts. Networks: packets: 14740498/18G in, 4783755/622M out. Disks: 772104/15G read, 772984/24G written. PID COMMAND %CPU TIME #TH #WQ #PORTS MEM PURG CMPRS PGRP PPID STATE BOOSTS %CPU_ME %CPU_OTHRS UID FAULTS COW 5390 top 3.1 00:00.47 1/1 0 23 5704K 0B 0B 5390 5344 running *0[1] 0.00000 0.00000 0 4165+ 104 5381 auditd 0.0 00:00.01 3 2 31- 644K- 0B 0B 5381 1 sleeping *0[1] 0.00000 0.00000 0 715+ 200 5344 bash 0.0 00:00.00 1 0 19 636K 0B 0B 5344 5343 sleeping *0[1] 0.00000 0.00000 505 633 177 5343 login 0.0 00:00.03 2 1 30 1100K 0B 0B 5343 5342 sleeping *0[9] 0.00000 0.00000 0 1578 178 ### Detach your screen session by pressing Ctrl+d ### Now your process is running in background on the screen session ### you can reattach with detached screen by using command "screen -r ID" ### where ID can be grepped from "screen -ls" command.
5. tmux command
tmux works similar to screen command.
a. Run “tmx” commmand.
b. A new shell session is started. Run the required command, say, “top”
c. Detach the session by pressing Ctrl+b and then d.
d. Check the running sessions with command “tmux list-sessions”
e. Attach to a session using command “tmux attach-session -t 0”.
1. nohup and & (Most widely used)
2. Screen command
3. tmx command