The retry command is used to repeat a command until it succeeds or until a specific criterion is met. This can be useful in situations where a command may fail temporarily and needs to be retried until it succeeds. The retry command provides options to set a delay between retries and to specify the maximum number of attempts before giving up.

Use case 1: Retry a command until it succeeds

Code:

retry command

Motivation: Sometimes, a command may fail due to temporary issues such as network problems or server unavailability. Instead of manually retrying the command multiple times, the retry command can be used to automate the process and keep retrying the command until it succeeds.

Explanation: In this use case, the retry command is used without any additional options. The command argument represents the command that needs to be retried until it succeeds. The retry command will continue executing the command until it returns a successful exit status (0).

Example Output:

Retrying command...
Retrying command...
Command executed successfully.

Use case 2: Retry a command every n seconds until it succeeds

Code:

retry --delay=n command

Motivation: In some scenarios, it is desirable to introduce a delay between retry attempts to avoid overwhelming the system or to give enough time for potential issues to be resolved. The --delay option allows specifying a delay between each retry attempt in seconds.

Explanation: In this use case, the --delay=n option is added to the retry command. The n represents the number of seconds to wait before each retry attempt. The command argument represents the command to be retried until it succeeds. The retry command will execute the command, wait for n seconds, and then retry again until it succeeds.

Example Output:

Retrying command...
Waiting for 5 seconds...
Retrying command...
Command executed successfully.

Use case 3: Give up after n attempts

Code:

retry --times=n command

Motivation: There might be cases where it is necessary to limit the number of retries to avoid an infinite loop or to set an upper limit for the number of attempts. The --times option allows specifying the maximum number of retry attempts.

Explanation: In this use case, the --times=n option is added to the retry command. The n represents the maximum number of retry attempts before giving up. The command argument represents the command to be retried until it succeeds. The retry command will execute the command repeatedly until it succeeds or until it has been retried n times.

Example Output:

Retrying command...
Retrying command...
Retrying command...
Maximum number of attempts reached. Giving up.

Conclusion:

The retry command is a handy utility for automating the retrying of commands until they succeed or a specific criterion is met. Whether it is for dealing with temporary failures or ensuring a maximum number of retries, the retry command provides flexibility and convenience in handling command execution.