Hello there, I would like to prevent one of my root process from deleting a certaing file. So I came across the flock command, it seems to fit my need, but I didnt get its sintax. If I only indicate a shared lock, it doesnt work: flock -s "./file.xml" If I add a timeout parameter, it still doesnt work flock -s -w5 "./file.xml" It seems that way, it fits in flock [-sxun][-w #] fd# way. (What is this fd# parameter?) So, I tried the flock [-sxon][-w #] file [-c] command Using flock -s -w5 "./file.xml" -c "tail -3 ./file.xml" and it worked, tail command at ./file.xml was executed. But I would like to know, does the lock end after the command or does it last 5 seconds after the end of the command execution? My main question is, how can I prevent another root process deleting a file in linux?