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10 .TH NOHUP 1 "Jun 19, 2006"
11 .SH NAME
12 nohup \- run a command immune to hangups
13 .SH SYNOPSIS
14 .LP
15 .nf
16 \fB/usr/bin/nohup\fR \fIcommand\fR [\fIargument\fR]...
17 .fi
19 .LP
20 .nf
21 \fB/usr/bin/nohup\fR \fB-p\fR [\fB-Fa\fR] \fIpid\fR [\fIpid\fR]...
22 .fi
24 .LP
25 .nf
26 \fB/usr/bin/nohup\fR \fB-g\fR [\fB-Fa\fR] \fIgpid\fR [\fIgpid\fR]...
27 .fi
29 .LP
30 .nf
31 \fB/usr/xpg4/bin/nohup\fR \fIcommand\fR [\fIargument\fR]...
32 .fi
34 .SH DESCRIPTION
35 .sp
36 .LP
37 The \fBnohup\fR utility invokes the named \fIcommand\fR with the arguments
38 supplied. When the \fIcommand\fR is invoked, \fBnohup\fR arranges for the
39 \fBSIGHUP\fR signal to be ignored by the process.
40 .sp
41 .LP
42 When invoked with the \fB-p\fR or \fB-g\fR flags, \fBnohup\fR arranges for
43 processes already running as identified by a list of process \fBID\fRs or a
44 list of process group \fBID\fRs to become immune to hangups.
45 .sp
46 .LP
47 The \fBnohup\fR utility can be used when it is known that \fIcommand\fR takes a
48 long time to run and the user wants to log out of the terminal. When a shell
49 exits, the system sends its children \fBSIGHUP\fR signals, which by default
50 cause them to be killed. All stopped, running, and background jobs ignores
51 \fBSIGHUP\fR and continue running, if their invocation is preceded by the
52 \fBnohup\fR command or if the process programmatically has chosen to ignore
53 \fBSIGHUP\fR.
54 .sp
55 .ne 2
56 .na
57 \fB\fB/usr/bin/nohup\fR\fR
58 .ad
59 .RS 27n
60 Processes run by \fB/usr/bin/nohup\fR are immune to \fBSIGHUP\fR (hangup) and
61 \fBSIGQUIT\fR (quit) signals.
62 .RE
64 .sp
65 .ne 2
66 .na
67 \fB\fB/usr/bin/nohup\fR \fB-p\fR [\fB-Fa\fR]\fR
68 .ad
69 .RS 27n
70 Processes specified by \fBID\fR are made immune to \fBSIGHUP\fR and
71 \fBSIGQUIT\fR, and all output to the controlling terminal is redirected to
72 \fBnohup.out\fR. If \fB-F\fR is specified, \fBnohup\fR forces control of each
73 process. If \fB-a\fR is specified, \fBnohup\fR changes the signal disposition
74 of \fBSIGHUP\fR and \fBSIGQUIT\fR even if the process has installed a handler
75 for either signal.
76 .RE
78 .sp
79 .ne 2
80 .na
81 \fB\fB/usr/bin/nohup\fR \fB-g\fR [\fB-Fa\fR]\fR
82 .ad
83 .RS 27n
84 Every process in the same process group as the processes specified by \fBID\fR
85 are made immune to \fBSIGHUP\fR and \fBSIGQUIT\fR, and all output to the
86 controlling terminal is redirected to \fBnohup.out\fR. If \fB-F\fR is
87 specified, \fBnohup\fR forces control of each process. If \fB-a\fR is
88 specified, \fBnohup\fR changes the signal disposition of \fBSIGHUP\fR and
89 \fBSIGQUIT\fR even if the process has installed a handler for either signal.
90 .RE
92 .sp
93 .ne 2
94 .na
95 \fB\fB/usr/xpg4/bin/nohup\fR\fR
96 .ad
97 .RS 27n
98 Processes run by \fB/usr/xpg4/bin/nohup\fR are immune to \fBSIGHUP\fR.
99 .sp
100 The \fBnohup\fR utility does not arrange to make processes immune to a
101 \fBSIGTERM\fR (terminate) signal, so unless they arrange to be immune to
102 \fBSIGTERM\fR or the shell makes them immune to \fBSIGTERM\fR, they will
103 receive it.
104 .sp
105 If \fBnohup.out\fR is not writable in the current directory, output is
106 redirected to \fB$HOME/nohup.out\fR. If a file is created, the file has read
107 and write permission (\fB600\fR. See \fBchmod\fR(1). If the standard error is a
108 terminal, it is redirected to the standard output, otherwise it is not
109 redirected. The priority of the process run by \fBnohup\fR is not altered.
110 .RE
112 .SH OPTIONS
113 .sp
114 .LP
115 The following options are supported:
116 .sp
117 .ne 2
118 .na
119 \fB\fB-a\fR\fR
120 .ad
121 .RS 6n
122 Always changes the signal disposition of target processes. This option is valid
123 only when specified with \fB-p\fR or \fB-g\fR.
124 .RE
126 .sp
127 .ne 2
128 .na
129 \fB\fB-F\fR\fR
130 .ad
131 .RS 6n
132 Force. Grabs the target processes even if another process has control. This
133 option is valid only when specified with \fB-p\fR or \fB-g.\fR
134 .RE
136 .sp
137 .ne 2
138 .na
139 \fB\fB-g\fR\fR
140 .ad
141 .RS 6n
142 Operates on a list of process groups. This option is not valid with \fB-p\fR.
143 .RE
145 .sp
146 .ne 2
147 .na
148 \fB\fB-p\fR\fR
149 .ad
150 .RS 6n
151 Operates on a list of processes. This option is not valid with \fB-g\fR.
152 .RE
154 .SH OPERANDS
155 .sp
156 .LP
157 The following operands are supported:
158 .sp
159 .ne 2
160 .na
161 \fB\fIpid\fR\fR
162 .ad
163 .RS 12n
164 A decimal process \fBID\fR to be manipulated by \fBnohup\fR \fB-p\fR.
165 .RE
167 .sp
168 .ne 2
169 .na
170 \fB\fIpgid\fR\fR
171 .ad
172 .RS 12n
173 A decimal process group \fBID\fR to be manipulated by \fBnohup\fR \fB-g\fR.
174 .RE
176 .sp
177 .ne 2
178 .na
179 \fB\fIcommand\fR\fR
180 .ad
181 .RS 12n
182 The name of a command that is to be invoked. If the \fIcommand\fR operand names
183 any of the special \fBshell_builtins\fR(1) utilities, the results are
184 undefined.
185 .RE
187 .sp
188 .ne 2
189 .na
190 \fB\fIargument\fR\fR
191 .ad
192 .RS 12n
193 Any string to be supplied as an argument when invoking the \fIcommand\fR
194 operand.
195 .RE
197 .SH USAGE
198 .sp
199 .LP
200 Caution should be exercised when using the \fB-F\fR flag. Imposing two
201 controlling processes on one victim process can lead to chaos. Safety is
202 assured only if the primary controlling process, typically a debugger, has
203 stopped the victim process and the primary controlling process is doing nothing
204 at the moment of application of the \fBproc\fR tool in question.
205 .SH EXAMPLES
206 .LP
207 \fBExample 1 \fRApplying nohup to pipelines or command lists
208 .sp
209 .LP
210 It is frequently desirable to apply \fBnohup\fR to pipelines or lists of
211 commands. This can be done only by placing pipelines and command lists in a
212 single file, called a shell script. One can then issue:
214 .sp
215 .in +2
216 .nf
217 example$ \fBnohup sh \fIfile\fR\fR
218 .fi
219 .in -2
220 .sp
222 .sp
223 .LP
224 and the \fBnohup\fR applies to everything in \fIfile\fR. If the shell script
225 \fIfile\fR is to be executed often, then the need to type \fBsh\fR can be
226 eliminated by giving \fIfile\fR execute permission.
228 .sp
229 .LP
230 Add an ampersand and the contents of \fIfile\fR are run in the background with
231 interrupts also ignored (see \fBsh\fR(1)):
233 .sp
234 .in +2
235 .nf
236 example$ \fBnohup \fIfile\fR &\fR
237 .fi
238 .in -2
239 .sp
241 .LP
242 \fBExample 2 \fRApplying nohup -p to a process
243 .sp
244 .in +2
245 .nf
246 example$ \fBlong_running_command &\fR
247 example$ \fBnohup -p `pgrep long_running_command`\fR
248 .fi
249 .in -2
250 .sp
252 .LP
253 \fBExample 3 \fRApplying nohup -g to a process group
254 .sp
255 .in +2
256 .nf
257 example$ \fBmake &\fR
258 example$ \fBps -o sid -p $$\fR
259 SID
260 81079
261 example$ \fBnohup -g `pgrep -s 81079 make`\fR
262 .fi
263 .in -2
264 .sp
266 .SH ENVIRONMENT VARIABLES
267 .sp
268 .LP
269 See \fBenviron\fR(5) for descriptions of the following environment variables
270 that affect the execution of \fBnohup\fR: \fBLANG\fR, \fBLC_ALL\fR,
271 \fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, \fBPATH\fR, \fBNLSPATH\fR, and \fBPATH\fR.
272 .sp
273 .ne 2
274 .na
275 \fB\fBHOME\fR\fR
276 .ad
277 .RS 8n
278 Determine the path name of the user's home directory: if the output file
279 \fBnohup.out\fR cannot be created in the current directory, the \fBnohup\fR
280 command uses the directory named by \fBHOME\fR to create the file.
281 .RE
283 .SH EXIT STATUS
284 .sp
285 .LP
286 The following exit values are returned:
287 .sp
288 .ne 2
289 .na
290 \fB\fB126\fR\fR
291 .ad
292 .RS 7n
293 \fIcommand\fR was found but could not be invoked.
294 .RE
296 .sp
297 .ne 2
298 .na
299 \fB\fB127\fR\fR
300 .ad
301 .RS 7n
302 An error occurred in \fBnohup\fR, or \fIcommand\fR could not be found
303 .RE
305 .sp
306 .LP
307 Otherwise, the exit values of \fBnohup\fR are those of the \fIcommand\fR
308 operand.
309 .SH FILES
310 .sp
311 .ne 2
312 .na
313 \fB\fBnohup.out\fR\fR
314 .ad
315 .RS 19n
316 The output file of the \fBnohup\fR execution if standard output is a terminal
317 and if the current directory is writable.
318 .RE
320 .sp
321 .ne 2
322 .na
323 \fB\fB$HOME/nohup.out\fR\fR
324 .ad
325 .RS 19n
326 The output file of the \fBnohup\fR execution if standard output is a terminal
327 and if the current directory is not writable.
328 .RE
330 .SH ATTRIBUTES
331 .sp
332 .LP
333 See \fBattributes\fR(5) for descriptions of the following attributes:
334 .SS "/usr/bin/nohup"
335 .sp
337 .sp
338 .TS
339 box;
340 c | c
341 l | l .
342 ATTRIBUTE TYPE ATTRIBUTE VALUE
343 _
344 CSI Enabled
345 .TE
347 .SS "/usr/xpg4/bin/nohup"
348 .sp
350 .sp
351 .TS
352 box;
353 c | c
354 l | l .
355 ATTRIBUTE TYPE ATTRIBUTE VALUE
356 _
357 CSI Enabled
358 _
359 Interface Stability Standard
360 .TE
362 .SH SEE ALSO
363 .sp
364 .LP
365 \fBbatch\fR(1), \fBchmod\fR(1), \fBcsh\fR(1), \fBksh\fR(1), \fBnice\fR(1),
366 \fBpgrep\fR(1), \fBproc\fR(1), \fBps\fR(1), \fBsh\fR(1),
367 \fBshell_builtins\fR(1), \fBsignal\fR(3C), \fBproc\fR(4), \fBattributes\fR(5),
368 \fBenviron\fR(5), \fBstandards\fR(5)
369 .SH WARNINGS
370 .sp
371 .LP
372 If you are running the Korn shell (\fBksh\fR(1)) as your login shell, and have
373 \fBnohup\fR'ed jobs running when you attempt to log out, you are warned with
374 the message:
375 .sp
376 .in +2
377 .nf
378 You have jobs running.
379 .fi
380 .in -2
381 .sp
383 .sp
384 .LP
385 You need to log out a second time to actually log out. However, your background
386 jobs continues to run.
387 .SH NOTES
388 .sp
389 .LP
390 The C-shell (\fBcsh\fR(1)) has a built-in command \fBnohup\fR that provides
391 immunity from \fBSIGHUP\fR, but does not redirect output to \fBnohup.out\fR.
392 Commands executed with `\fB&\fR\&' are automatically immune to \fBHUP\fR
393 signals while in the background.
394 .sp
395 .LP
396 \fBnohup\fR does not recognize command sequences. In the case of the following
397 command,
398 .sp
399 .in +2
400 .nf
401 example$ \fBnohup command1; command2\fR
402 .fi
403 .in -2
404 .sp
406 .sp
407 .LP
408 the \fBnohup\fR utility applies only to \fBcommand1\fR. The command,
409 .sp
410 .in +2
411 .nf
412 example$ \fBnohup (command1; command2)\fR
413 .fi
414 .in -2
415 .sp
417 .sp
418 .LP
419 is syntactically incorrect.