1lockfile-progs(1) Lockfile programs lockfile-progs(1)
2
6 lockfile-progs - command-line programs to safely lock and unlock files
7 and mailboxes (via liblockfile).
8
10 mail-lock [--use-pid] [--retry retry-count]
11 mail-unlock
12 mail-touchlock [--oneshot]
13 lockfile-create [--use-pid] [--retry retry-count] [--lock-name] filename
15 lockfile-remove [--lock-name] filename
16 lockfile-touch [--oneshot] [--lock-name] filename
17 lockfile-check [--use-pid] [--lock-name] filename
18
20 Lockfile-progs provides a set a programs that can be used to lock and
21 unlock mailboxes and files safely (via liblockfile):
22 mail-lock - lock the current user's mailbox
24 mail-unlock - unlock the current user's mailbox
25 mail-touchlock - touch the lock on the current user's mailbox
26 lockfile-create - lock a given file
28 lockfile-remove - remove the lock on a given file
29 lockfile-touch - touch the lock on a given file
30 lockfile-check - check the lock on a given file
31 By default, the filename argument refers to the name of the file to be
33 locked, and the name of the lockfile will be filename .lock. However,
34 if the --lock-name argument is specified, then filename will be taken
35 as the name of the lockfile itself.
36 Each of the mail locking commands attempts to lock
38 /var/spool/mail/<user>, where <user> is the name associated with the
39 effective user ID, as determined by via geteuid(2).
40 Once a file is locked, the lock must be touched at least once every
42 five minutes or the lock will be considered stale, and subsequent lock
43 attempts will succeed. Also see the --use-pid option and the lock‐
44 file_create(3) manpage.
45 The lockfile-check command tests whether or not a valid lock already
47 exists.
48
51 -q, --quiet
52 Suppress any output. Success or failure will only be indicated by
53 the exit status.
54 -v, --verbose
56 Enable diagnostic output.
57 -l, --lock-name
59 Do not append .lock to the filename. This option applies to lock‐
60 file-create, lockfile-remove, lockfile-touch, or lockfile-check.
61 -p, --use-pid
63 Write the parent process id (PPID) to the lockfile whenever a lock‐
64 file is created, and use that pid when checking a lock's validity.
65 See the lockfile_create(3) manpage for more information. This
66 option applies to lockfile-create and lockfile-check. NOTE: this
67 option will not work correctly between machines sharing a filesys‐
68 tem.
69 -o, --oneshot
71 Touch the lock and exit immediately. This option applies to lock‐
72 file-touch and mail-touchlock. When not provided, these commands
73 will run forever, touching the lock once every minute until killed.
74 -r retry-count, --retry retry-count
76 Try to lock filename retry-count times before giving up. Each
77 attempt will be delayed a bit longer than the last (in 5 second
78 increments) until reaching a maximum delay of one minute between
79 retries. If retry-count is unspecified, the default is 9 which
80 will give up after 180 seconds (3 minutes) if all 9 lock attempts
81 fail.
82
85 Locking a file during a lengthy process:
86 lockfile-create /some/file
88 lockfile-touch /some/file &
89 # Save the PID of the lockfile-touch process
90 BADGER="$!"
91 do-something-important-with /some/file
92 kill "${BADGER}"
93 lockfile-remove /some/file
94
97 0
98 For lockfile-check this indicates that a valid lock exists, other‐
99 wise it just indicates successful program execution.
100 Not 0
102 For lockfile-check a non-zero exit status indicates that the speci‐
103 fied lock does not exist or is not valid. For other programs it
104 indicates that some problem was encountered.
105
107 maillock(3)
108 touchlock(3)
109 mailunlock(3)
110 lockfile_create(3)
111 lockfile_remove(3)
112 lockfile_touch(3)
113 lockfile_check(3)
114
117 Written by Rob Browning <rlb@defaultvalue.org>
1180.1.12 2008-02-10 lockfile-progs(1)