How to timeout user input in Linux Bash Shell ?

In Linux, we use read command to take the user input.

However sometimes, we may need to timeout the user input to automate the script execution in case no one is available.

For this, we can use timeout option of read command.

Timeout User Input

### Timeout in 5 seconds if no input received.
[root@nglinux ~]# read -t5 -p "Enter Your Name: "; echo
Enter Your Name: 
[root@nglinux ~]# 

In the above command, we have used “-t” option to set timeout to 5 seconds.

From the man page of timeout, we can read its description as follows:

-t timeout
                     Cause read to time out and return fail-
                     ure  if a complete line of input is not
                     read within timeout  seconds.   timeout
                     may  be  a  decimal number with a frac-
                     tional portion  following  the  decimal
                     point.   This  option is only effective
                     if read is reading input from a  termi-
                     nal,  pipe,  or  other special file; it
                     has no effect when reading from regular
                     files.   If  timeout is 0, read returns
                     success if input is  available  on  the
                     specified file descriptor, failure oth-
                     erwise.  The  exit  status  is  greater
                     than 128 if the timeout is exceeded.

Hence we can use this option and mention number of seconds after which we want the script to timeout and proceed further.

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