watch command

monitors changes in command output

Typical usage: diagnosing problems, monitoring, troubleshooting

Installation
Usage
- Options
Examples

Introduction into watch

The watch command is one of those small Linux utilities that come in handy at times. It runs a command with a specified interval and shows its output. This is useful during troubleshooting, for example when you are interested in monitoring a directory for changes. Although you can define a ‘watch’ with the Linux Audit Framework, it is quicker to run this command instead.

Installation

When watch is not installed by default, it can be added to the system using the relevant software package.

Package information for watch

Operating system	Package name	Installation
AlmaLinux	procps-ng	`dnf install procps-ng`
Arch Linux	procps-ng	`pacman -S procps-ng`
Debian	procps	`apt install procps`
Fedora	procps-ng	`dnf install procps-ng`
Red Hat Enterprise Linux	procps-ng	`dnf install procps-ng`
Rocky Linux	procps-ng	`dnf install procps-ng`
openSUSE	procps	`zypper install procps`
Ubuntu	procps	`apt install procps`

Your Linux distribution using a different package? Share your feedback.

Usage

Available options

Long option	Short option	Description
--beep	-b	Beep on error (based on exit code)
--differences[=permanent]	-d	Show the differences in output. When using the optional '=permanent', the differences between the original output and last refresh will stay marked.
--no-title	-t	Don't use header with title, refresh interval, so only command output remains
--no-wrap	-w	No wrapping of lines that are too long
--version	-v	Show version information

Missing an option in this overview? Share your feedback.

Examples using watch

File systems and directories

Show differences within a directory, mark items that changes

watch --differences=permanent ls -l

Monitor directory with most recently changed files on top

watch ls -alt

Monitor available disk space, especially useful during batch operations

watch df -h

Monitor current directory size (in megabytes)

watch du -sm

Monitor if a mount point is still in use

watch fuser --verbose --mount /mnt/backups

Networking

Show network connection statistics with a refresh every second

watch --interval=1 ss -s

Hardware

Monitor temperature changes (requires sensors command)

watch sensors

Frequently Asked Questions

What is the watch command and its purpose?

The watch command is a command-line tool to watch changes in the output of commands to assist with monitoring and troubleshooting.

Which package provides the watch command?

The command watch is provided by the procps or procps-ng package.

Related and similar commands

Linux has a lot of tools and commands available and sometimes you just need that little other tool. Here is a list of commands that are similar or related to watch:

Related and similar commands to watch
Command	Category	Summary
basename	files	Strips directory and file name suffix from a given path
chrt	processes	Sets Linux scheduler policy and priority for a process or command
fuser	files and sockets	Show processes using a file or socket
kill	processes	Sending signals to processes
lsfd	files	Shows open file descriptors for processes
nice	processes	Runs commands with specified priority
numactl	processes	Controls NUMA policy for processes and shared memory
peekfd	processes	Tracks a process and show file descriptor activity
pidof	processes	Returns process IDs for a process name
pidstat	monitoring	Monitoring CPU, memory, and disk activity
pidwait	processes	Wait for process to stop
pmap	processes	Shows memory mapping of process
prtstat	processes	Shows process details for selected process like state, CPU and memory usage
pscap	capabilities	Display available capabilities for running processes
pslog	logging	Shows which log files a process has opened
pstree	processes	Show active processes and children like a tree
pwdx	processes	Shows current working directory of a process
renice	processes	Changes the priority of running processes
slabtop	memory	Shows slab usage of kernel
smem	memory	Show memory usage including swap
strace	process inspection	Inspects running process
units	data conversion	Converts a unit into another one, like from Celcius to Fahrenheit