SugiDBA: Linux Watch Command

Linux Watch Command

Watch Command is used to run commands at regular intervals like 10 sec,1 mins, etc . This is alternate to cron command.

watch [option] [command]

Where:

[option]: Adding an option changes the way the watch command behaves. Available options are listed below.
[command]: A user-defined command you want to run repeatedly.

The watch command options include:

`-n`, `--interval`	Allows you to specify the interval between output updates.
`-d`, `--differences`	Highlights the differences between output updates.
`-g`, `--chgexit`	Exits the `watch` command when the output of the user-defined command changes.
`-t`, `--no-title`	Removes the header showing the interval, command, and current time and date.
`-b`, `--beep`	Plays a sound alert (beep) if the command exits with an error.
`-p`, `--precise`	Attempts to run the command after the exact number of seconds defined by the `--interval` option.
`-e`, `--errexit`	Stops output updates on error and exits the command after a key press.
`-c`, `--color`	Interprets ANSI color and style sequences.
`-x`, `--exec`	Passes the user-defined command to `exec`, reducing the need for extra quoting.
`-w`, `--no-linewrap`	Turns off line wrapping and truncates long lines instead.
`-h`, `--help`	Displays help text and exits.
`-v`, `--version`	Displays version information and exits.

Here are some of the ways you can use the watch command options to achieve different results:

Set a custom interval to run a user-defined command and show the output by using the -n or --interval option:

watch -n [interval in seconds] [command]

For instance, to display the system time and date every 5 seconds, run:

watch -n 5 date

Use the -n option to set a custom interval

For ORACLE DBA

watch -n 30 dcli -l root -g /u01/onecommand/dbs_group uptime

Note: Above Command will run for every 30 sec

To highlight the difference between previous and current output

watch -n 5 -d date