dotlockfile - Utility to manage lockfiles
/usr/bin/dotlockfile [-p] [-c] [-u] [-m] [-l|-u] [-r retries] [lock-
Dotlockfile is a command line utility to safely create, test and remove
lockfiles. Lockfiles are created in an NFS-safe way. Dotlockfile can
lock and unlock mailboxes even if the mailspool directory is only
writable by group mail.
The name dotlockfile comes from the way mailboxes are locked for
updates on a lot of UNIX systems. A lockfile is created with the same
filename as the mailbox but with the string ".lock" appended.
The names dotlock and lockfile were already taken - hence the name dot-
-l Create a lockfile. This is the default.
-u Remove a lockfile.
-c Check for the existence of a valid lockfile.
-p Write the process-id of the calling process into the lockfile.
Also when testing for an existing lockfile, check the contents
for a process-id to find out if the lockfile is still valid.
The number of times dotlockfile tries to acquire the lock before
giving up. The initial sleep after failing to acquire the lock
is 5 seconds. After each next try, a sleep of 5 seconds extra
occurs up to a maximum sleep of 60 seconds between tries.
-m Lock or unlock the current users mailbox. The path to the mailbox
is the default system mailspool directory (usually
/var/mail) with the username as gotten from getpwuid() appended.
If the environment variable $MAIL is set, that is used instead.
Then the string ".lock" is appended to get the name of the
The lockfile to be created/removed, unless the -m option is in
Zero on success, and non-zero on failure. For the -c option, sucess
means that a valid lockfile is already present. When locking (the
default, or the -l option) dotlockfile returns the same values as the
library function lockfile_create(3).
The lockfile is created exactly as named on the command line. The
extension .lock is not automatically added.
This utility is a lot like the lockfile(1) utility included with proc-
mail, and the mutt_dotlock(1) utility included with mutt. However the
command-line arguments differ, and so does the return status. It is
believed that dotlockfile is the most flexible implementation, since it
automatically detects when it needs to use priviliges to lock a mailbox,
and does it safely.
Miquel van Smoorenburg, firstname.lastname@example.org
05 June 1999 DOTLOCKFILE(1)
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