If condition based on tail and grep commands in Shell Script

Question

I want to write an if condition in Shell script something like this:

if[ tail -10f logFile | grep -q "RUNNING" ]

So the idea is I have restarted my server and want to perform some action only after the server is started up(RUNNING). So I want to continuously tail the log and check if the server is in RUNNING mode again.

The issue with the above approach is it does not exits even after the server is RUNNING and goes into infinite loop. No code in if or else is printed.

Harold · Accepted Answer · 2018-08-14 13:13:57Z

1

What about?

while [ $(tail -10 logFile | grep -c RUNNING) -eq 0 ]; do sleep 1; done

answered Aug 14, 2018 at 13:13

Harold

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2 Comments

Dada Over a year ago

And if 11 lines were logged while you were sleeping?

Benjamin W. Over a year ago

Instead of [ $(...) -eq 0 ], you could use while ! tail [...] | grep -q RUNNING; do, i.e., use the exit status directly.

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