CODEWITHSUNDEEP
bashshellunixflock
Vijay Shekhawat
Vijay Shekhawat

Reputation: 159

How can I check if a file is locked by other process?

I am using Flock to get an exclusive lock on a text file and write something in it, before doing that I want to check if some other process has any kind of lock on that file, if so then I would like to do something else rather be in the queue which is default action in flock.

So, I want something like 

if locked; then
    do something

else
    ( 
    flock -e 200
    echo "In critical section"
    echo text >> file.txt
    echo text added to File 
    )   200>file.txt

is there a way in bash to check this? I have looked into lsof but I am not able to arrive at solution.

Upvotes: 1

Views: 5226

Answers (1)

Peter Faller
Peter Faller

Reputation: 132

Try using ...

( flock -n 200 || exit 1
  echo "In critical section"
  echo text >> file.txt
  echo text added to File 
) 200>file.txt

The '-n' flag will prevent blocking, and the exit code will be '1' if the lock was not obtained.

Upvotes: 1

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