Why use “lock file” instead of a programmable lock?

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Mark says at https://unix.stackexchange.com/a/467795/




One use for O_EXCL and O_CREAT with open() is to create a simple lock file. If multiple processes try to open the same file with the O_CREAT and O_EXCL flags, one will succeed and the rest will fail. Of course, if the file already exists, for example because a previous process exited without removing the file, none of the subsequent attempts will succeed, so this is not the most robust way to manage a lock.




What does "lock file" mean?
The quote seems to me that the program which creates a lock file should delete it before termination. If so, is a lock file not used for storing meaning data, but for some other purpose?



It seems a lock file is used as a lock to synchronize several processes.
What is the benefits and disadvantages of using a lock file compared to using a lock in source code?



Thanks.






files io lock







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  • unix.stackexchange.com/q/143676/117549 and unix.stackexchange.com/q/12815/117549 and unix.stackexchange.com/q/22044/117549
    – Jeff Schaller
    8 mins ago










  • Possible duplicate of What are pid and lock files for?
    – Jeff Schaller
    8 mins ago














up vote
0
down vote

favorite












Mark says at https://unix.stackexchange.com/a/467795/




One use for O_EXCL and O_CREAT with open() is to create a simple lock file. If multiple processes try to open the same file with the O_CREAT and O_EXCL flags, one will succeed and the rest will fail. Of course, if the file already exists, for example because a previous process exited without removing the file, none of the subsequent attempts will succeed, so this is not the most robust way to manage a lock.




What does "lock file" mean?
The quote seems to me that the program which creates a lock file should delete it before termination. If so, is a lock file not used for storing meaning data, but for some other purpose?



It seems a lock file is used as a lock to synchronize several processes.
What is the benefits and disadvantages of using a lock file compared to using a lock in source code?



Thanks.






files io lock







share|improve this question























  • unix.stackexchange.com/q/143676/117549 and unix.stackexchange.com/q/12815/117549 and unix.stackexchange.com/q/22044/117549
    – Jeff Schaller
    8 mins ago










  • Possible duplicate of What are pid and lock files for?
    – Jeff Schaller
    8 mins ago












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Mark says at https://unix.stackexchange.com/a/467795/




One use for O_EXCL and O_CREAT with open() is to create a simple lock file. If multiple processes try to open the same file with the O_CREAT and O_EXCL flags, one will succeed and the rest will fail. Of course, if the file already exists, for example because a previous process exited without removing the file, none of the subsequent attempts will succeed, so this is not the most robust way to manage a lock.




What does "lock file" mean?
The quote seems to me that the program which creates a lock file should delete it before termination. If so, is a lock file not used for storing meaning data, but for some other purpose?



It seems a lock file is used as a lock to synchronize several processes.
What is the benefits and disadvantages of using a lock file compared to using a lock in source code?



Thanks.






files io lock







share|improve this question















Mark says at https://unix.stackexchange.com/a/467795/




One use for O_EXCL and O_CREAT with open() is to create a simple lock file. If multiple processes try to open the same file with the O_CREAT and O_EXCL flags, one will succeed and the rest will fail. Of course, if the file already exists, for example because a previous process exited without removing the file, none of the subsequent attempts will succeed, so this is not the most robust way to manage a lock.




What does "lock file" mean?
The quote seems to me that the program which creates a lock file should delete it before termination. If so, is a lock file not used for storing meaning data, but for some other purpose?



It seems a lock file is used as a lock to synchronize several processes.
What is the benefits and disadvantages of using a lock file compared to using a lock in source code?



Thanks.






files io lock




files io lock






share|improve this question















share|improve this question













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edited 2 mins ago

























asked 17 mins ago









Tim

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  • unix.stackexchange.com/q/143676/117549 and unix.stackexchange.com/q/12815/117549 and unix.stackexchange.com/q/22044/117549
    – Jeff Schaller
    8 mins ago










  • Possible duplicate of What are pid and lock files for?
    – Jeff Schaller
    8 mins ago
















  • unix.stackexchange.com/q/143676/117549 and unix.stackexchange.com/q/12815/117549 and unix.stackexchange.com/q/22044/117549
    – Jeff Schaller
    8 mins ago










  • Possible duplicate of What are pid and lock files for?
    – Jeff Schaller
    8 mins ago















unix.stackexchange.com/q/143676/117549 and unix.stackexchange.com/q/12815/117549 and unix.stackexchange.com/q/22044/117549
– Jeff Schaller
8 mins ago




unix.stackexchange.com/q/143676/117549 and unix.stackexchange.com/q/12815/117549 and unix.stackexchange.com/q/22044/117549
– Jeff Schaller
8 mins ago












Possible duplicate of What are pid and lock files for?
– Jeff Schaller
8 mins ago




Possible duplicate of What are pid and lock files for?
– Jeff Schaller
8 mins ago















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