timeout Linux command

The timeout command in Linux allows users to run other commands with a specified time limit, after which the command will be terminated. This can help prevent commands from running indefinitely and consuming system resources. The syntax for the timeout command is simple, requiring only the desired duration and the command to be executed. Users can also customize the behavior of the timeout command by specifying what signal to send when the time limit is reached. This functionality can be useful for automating tasks, managing system resources, and ensuring that processes do not cause system slowdowns or crashes.

timeout Syntax:

timeout [option] [duration] [command]

Options:

Option	Description
-s	Specify a different signal to send
-k	Kill the process after the timeout
—preserve-status	Return the command’s exit status
—foreground	Run the command in the foreground instead of the background

Parameters:

Parameter	Description
duration	Timeout duration in seconds
command	Command to execute with the timeout

Caution

Always ensure that the ‘timeout’ command is used responsibly to prevent unintended consequences such as prematurely terminating critical processes or systems.

timeout bash Examples:

Run a Command with a Time Limit

timeout 5s ls -l

Runs the “ls -l” command with a time limit of 5 seconds.

Terminate a Command After a Specific Duration

timeout 3m sleep 10

Terminates the sleep command after 3 minutes.

Display Custom Error Message with Timeout

timeout --kill-after=8s --signal=KILL 6s ping google.com

Runs the ping command for 6 seconds and sends a KILL signal if it exceeds 8 seconds.

Run a Command in the Background with Timeout

timeout 10s bash -c "sleep 15" &

Runs the sleep command with a duration of 15 seconds in the background, terminating it after 10 seconds.

Specify Timeout in Minutes

timeout 2m ls

Runs the ls command with a timeout of 2 minutes.

Use a Different Signal for Timeout

timeout --signal=SIGTERM 3s find / -name "*.txt"

Runs the find command with a timeout of 3 seconds, using the SIGTERM signal for termination.

Tip

When using the timeout command in Linux, be mindful of the execution time limit you set to prevent unexpected termination of processes. Always test the command with a suitable timeout value before using it in production environments.

timeout Command Help Center:

How do I use timeout in Linux?

To use the timeout command in Linux, execute the following command:

timeout --option <value>

How can I specify the timeout duration in seconds?

You can specify the timeout duration in seconds by providing the value directly in the command. For example:

timeout 10s <command>

Can I send a specific signal to the process when it times out?

Yes, you can send a specific signal to the process when it times out using the --signal option. Here’s an example:

timeout --signal=SIGTERM 5s <command>

Is there a default signal sent when no specific signal is provided for timeout?

By default, when no signal is specified for timeout, a SIGTERM signal is sent to the process. Here’s an example:

timeout 3s <command>

How do I ignore the exit status of the command being run with timeout?

If you want to ignore the exit status of the command run with timeout, you can use the --preserve-status option. For example:

timeout --preserve-status 5s <command>

Can I show a custom message when the command times out with timeout?

Yes, you can display a custom message when the command times out using the --foreground option along with the --kill-after option. Here’s an example:

timeout --foreground --kill-after=10s 15s <command>

How can I prevent timeout from killing commands in a subshell?

To prevent timeout from killing commands in a subshell, add exec before the command. For example:

timeout 10s exec <command>

How do I display help information for the timeout command?

You can view the help information for the timeout command by using the --help option. Here’s an example:

timeout --help

Applications of the timeout command

• Limiting the execution time of a command or script
• Monitoring long-running processes
• Automating tasks by setting a specific time limit
• Preventing resource exhaustion caused by processes running indefinitely
• Controlling the duration of a command’s execution