1halockrun(1) HA-Tools halockrun(1)
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6 halockrun - Run command while hold exclusive lock on file.
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9 halockrun [-ancf] [-e exitcode] [-E nexitcode] lockfile command [args]
10 halockrun -t [-c] [-e exitcode] [-E nexitcode] lockfile
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13 Executes the given command with the given args while holding an exclu‐
14 sive lock on the file lockfile halockrun will wait until the lock was
15 released and execute the command afterwards.
16 This is useful to serialize command execution from a shell script.
18 halockrun is implemented using locks from the operating system which
20 makes it very reliable and not vulnerable to dead locks.
21 halockrun can also be used to implement start/stop script's without
23 having pid-files.
24 -a Async mode. Starts the command in the background. The hatimerun
27 program exits immediately. The returncode of the executed com‐
28 mand is lost.
29 -c Create mode. Creates the lockfile if it doesn't exist. The
31 default behavior is to exit with exitcode if the specified lock‐
32 file doesn't exist.
33 -e exitcode
35 Changes the exitcode returned by halockrun on fail to exitcode
36 The default value for this option is 99
38 -E nexitcode
41 Changes the exitcode returned by halockrun in nonblocking or
42 testing mode if the lock can't be obtained to nexitcode
43 The default value for this option is exitcode in nonblocking
45 mode and 1 in testing mode.
46 -n Nonblocking mode. Exits with nexitcode if the lockfile is locked
49 by another Process.
50 -f Fork mode. The normal behavior of halockrun is to get the lock
52 and call execvp(2) to execute the command specified. If this
53 option is specified, halockrun will do a fork(2) and run the
54 command in its own process. In this case the parent ( halockrun
55 ) itself holds the lock on the lockfile. This may cause some
56 troubles if the halockrun process dies and the child is not fin‐
57 ished yet, in that case the child would not be protected. To
58 minimize this risk the halockrun process holding the lock
59 ignores the following signals: TERM, HUP, INT, PIPE, QUIT, USR1
60 and USR2.
61 This option is only useful to make sure that the command does
63 not see any difference when running under protection of halock‐
64 run. The only thing which is different (currently) when not
65 running with the -f option is that there is another open file‐
66 handle which is connected to the lockfile and holds the lock.
67 This option is new to version V0.99.08, before this version
69 halockrun has always made a fork. The default has changed
70 because it is much more important to make sure to not lose the
71 lock by accident then to make halockrun 100% transparent.
72 If you are in doubt about this option: don't use it.
74 -t Test mode. Can be used to check if the lockfile is currently
76 locked. If you specify this option halockrun will check if the
77 file is locked and return 0 if it is not locked or nexitcode if
78 it is locked and will print the pid of the process which holds
79 the lock to stdout. Regardless of the lockstatus, halockrun
80 will not run any command.
81 If an error occurs (e.g. because the lockfile doesn't exists)
83 exitcode will be returned.
84 Please note that if another halockrun is currently holing the
86 lock, you will receive the pid of the halockrun process which
87 holds the lock. This is usually the program which you run under
88 protection of halockrun but might be the halockrun process
89 itself if you have specified the -f flag.
90 When the -t flags is specified the flags -a, -n and -f are mean‐
92 ingless and will be ignored if the are specified.
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96 On success (if the command was executed) halockrun returns the return‐
97 value of the given command
98 On fail (e.g. if the lockfile doesn't exist or the command can't be
100 executed) halockrun returns the value specified by the -e option.
101 On failure to obtain the lock in testing mode or in nonblocking mode
103 halockrun returns the values specified by the -E option.
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107 Copyright (c) 2001,2003,2005-2007 by Markus Winand <mws@fatalmind.com>
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110 hatimerun(1)
111V2.00 $Date: 2007/08/18 15:38:13 $ halockrun(1)