Updated: 28 September 2026 · Applies to: Ubuntu 24.04, Debian 12, AlmaLinux 9 and Rocky Linux 9
These tools measure how long a command or process runs. They work on Ubuntu 24.04, Debian 12, AlmaLinux 9 and Rocky Linux 9.
time: measure a command
time tar czf backup.tar.gz /var/www
- real: wall-clock time from start to end.
- user: CPU time spent in the program.
- sys: CPU time spent in the kernel for the program.
If real is much larger than user + sys, the program was waiting (for disk, network or locks).
/usr/bin/time -v: more details
dnf install time # or: apt install time /usr/bin/time -v php script.php
Shows the maximum memory used, page faults, context switches and the exit status as well.
How long has a process been running?
ps -o pid,etime,cmd -p 1234 # elapsed time as [[dd-]hh:]mm:ss ps -eo pid,etimes,cmd --sort=-etimes | head # longest-running processes (seconds)
Boot and service start times
systemd-analyze # total boot time systemd-analyze blame | head # slowest services
