diff options
Diffstat (limited to 'man-pages-posix-2013/man1p/nohup.1p')
| -rw-r--r-- | man-pages-posix-2013/man1p/nohup.1p | 311 |
1 files changed, 311 insertions, 0 deletions
diff --git a/man-pages-posix-2013/man1p/nohup.1p b/man-pages-posix-2013/man1p/nohup.1p new file mode 100644 index 0000000..13e18f5 --- /dev/null +++ b/man-pages-posix-2013/man1p/nohup.1p @@ -0,0 +1,311 @@ +'\" et +.TH NOHUP "1P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. + +.SH NAME +nohup +\(em invoke a utility immune to hangups +.SH SYNOPSIS +.LP +.nf +nohup \fIutility \fB[\fIargument\fR...\fB]\fR +.fi +.SH DESCRIPTION +The +.IR nohup +utility shall invoke the utility named by the +.IR utility +operand with arguments supplied as the +.IR argument +operands. At the time the named +.IR utility +is invoked, the SIGHUP signal shall be set to be ignored. +.P +If standard input is associated with a terminal, the +.IR nohup +utility may redirect standard input from an unspecified file. +.P +If the standard output is a terminal, all output written by the named +.IR utility +to its standard output shall be appended to the end of the file +.BR nohup.out +in the current directory. If +.BR nohup.out +cannot be created or opened for appending, the output shall be appended +to the end of the file +.BR nohup.out +in the directory specified by the +.IR HOME +environment variable. If neither file can be created or opened for +appending, +.IR utility +shall not be invoked. If a file is created, the file's permission bits +shall be set to S_IRUSR | S_IWUSR. +.P +If standard error is a terminal and standard output is open but is not +a terminal, all output written by the named utility to its standard +error shall be redirected to the same open file description as the +standard output. If standard error is a terminal and standard output +either is a terminal or is closed, the same output shall instead be +appended to the end of the +.BR nohup.out +file as described above. +.SH OPTIONS +None. +.SH OPERANDS +The following operands shall be supported: +.IP "\fIutility\fR" 10 +The name of a utility that is to be invoked. If the +.IR utility +operand names any of the special built-in utilities in +.IR "Section 2.14" ", " "Special Built-In Utilities", +the results are undefined. +.IP "\fIargument\fR" 10 +Any string to be supplied as an argument when invoking the utility +named by the +.IR utility +operand. +.SH STDIN +Not used. +.SH "INPUT FILES" +None. +.SH "ENVIRONMENT VARIABLES" +The following environment variables shall affect the execution of +.IR nohup : +.IP "\fIHOME\fP" 10 +Determine the pathname of the user's home directory: if the output +file +.BR nohup.out +cannot be created in the current directory, the +.IR nohup +utility shall use the directory named by +.IR HOME +to create the file. +.IP "\fILANG\fP" 10 +Provide a default value for the internationalization variables that are +unset or null. (See the Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 8.2" ", " "Internationalization Variables" +for the precedence of internationalization variables used to determine +the values of locale categories.) +.IP "\fILC_ALL\fP" 10 +If set to a non-empty string value, override the values of all the +other internationalization variables. +.IP "\fILC_CTYPE\fP" 10 +Determine the locale for the interpretation of sequences of bytes of +text data as characters (for example, single-byte as opposed to +multi-byte characters in arguments). +.IP "\fILC_MESSAGES\fP" 10 +.br +Determine the locale that should be used to affect the format and +contents of diagnostic messages written to standard error. +.IP "\fINLSPATH\fP" 10 +Determine the location of message catalogs for the processing of +.IR LC_MESSAGES . +.IP "\fIPATH\fP" 10 +Determine the search path that is used to locate the utility to be +invoked. See the Base Definitions volume of POSIX.1\(hy2008, +.IR "Chapter 8" ", " "Environment Variables". +.SH "ASYNCHRONOUS EVENTS" +The +.IR nohup +utility shall take the standard action for all signals except that +SIGHUP shall be ignored. +.SH STDOUT +If the standard output is not a terminal, the standard output of +.IR nohup +shall be the standard output generated by the execution of the +.IR utility +specified by the operands. Otherwise, nothing shall be written to the +standard output. +.SH STDERR +If the standard output is a terminal, a message shall be written to the +standard error, indicating the name of the file to which the output is +being appended. The name of the file shall be either +.BR nohup.out +or +.BR $HOME/nohup.out . +.SH "OUTPUT FILES" +Output written by the named utility is appended to the file +.BR nohup.out +(or +.BR $HOME/nohup.out ), +if the conditions hold as described in the DESCRIPTION. +.SH "EXTENDED DESCRIPTION" +None. +.SH "EXIT STATUS" +The following exit values shall be returned: +.IP 126 8 +The utility specified by +.IR utility +was found but could not be invoked. +.IP 127 8 +An error occurred in the +.IR nohup +utility or the utility specified by +.IR utility +could not be found. +.P +Otherwise, the exit status of +.IR nohup +shall be that of the utility specified by the +.IR utility +operand. +.SH "CONSEQUENCES OF ERRORS" +Default. +.LP +.IR "The following sections are informative." +.SH "APPLICATION USAGE" +The +.IR command , +.IR env , +.IR nice , +.IR nohup , +.IR time , +and +.IR xargs +utilities have been specified to use exit code 127 if an error occurs +so that applications can distinguish ``failure to find a utility'' from +``invoked utility exited with an error indication''. The value 127 was +chosen because it is not commonly used for other meanings; most +utilities use small values for ``normal error conditions'' and the +values above 128 can be confused with termination due to receipt of a +signal. The value 126 was chosen in a similar manner to indicate that +the utility could be found, but not invoked. Some scripts produce +meaningful error messages differentiating the 126 and 127 cases. The +distinction between exit codes 126 and 127 is based on KornShell +practice that uses 127 when all attempts to +.IR exec +the utility fail with +.BR [ENOENT] , +and uses 126 when any attempt to +.IR exec +the utility fails for any other reason. +.SH EXAMPLES +It is frequently desirable to apply +.IR nohup +to pipelines or lists of commands. This can be done by placing +pipelines and command lists in a single file; this file can then be +invoked as a utility, and the +.IR nohup +applies to everything in the file. +.P +Alternatively, the following command can be used to apply +.IR nohup +to a complex command: +.sp +.RS 4 +.nf +\fB +nohup sh \(mic '\fIcomplex-command-line\fP' </dev/null +.fi \fR +.P +.RE +.SH RATIONALE +The 4.3 BSD version ignores SIGTERM and SIGHUP, and if +.BR ./nohup.out +cannot be used, it fails instead of trying to use +.BR $HOME/nohup.out . +.P +The +.IR csh +utility has a built-in version of +.IR nohup +that acts differently from the +.IR nohup +defined in this volume of POSIX.1\(hy2008. +.P +The term +.IR utility +is used, rather than +.IR command , +to highlight the fact that shell compound commands, pipelines, special +built-ins, and so on, cannot be used directly. +However, +.IR utility +includes user application programs and shell scripts, not just the +standard utilities. +.P +Historical versions of the +.IR nohup +utility use default file creation semantics. Some more recent versions +use the permissions specified here as an added security precaution. +.P +Some historical implementations ignore SIGQUIT in addition to SIGHUP; +others ignore SIGTERM. An early proposal allowed, but did not require, +SIGQUIT to be ignored. Several reviewers objected that +.IR nohup +should only modify the handling of SIGHUP as required by this volume of POSIX.1\(hy2008. +.P +Historical versions of +.IR nohup +did not affect standard input, but that causes problems in the common +scenario where the user logs into a system, types the command: +.sp +.RS 4 +.nf +\fB +nohup make & +.fi \fR +.P +.RE +.P +at the prompt, and then logs out. If standard input is not affected by +.IR nohup , +the login session may not terminate for quite some time, since standard +input remains open until +.IR make +exits. To avoid this problem, POSIX.1\(hy2008 allows implementations to +redirect standard input if it is a terminal. Since the behavior is +implementation-defined, portable applications that may run into the +problem should redirect standard input themselves. For example, +instead of: +.sp +.RS 4 +.nf +\fB +nohup make & +.fi \fR +.P +.RE +.P +an application can invoke: +.sp +.RS 4 +.nf +\fB +nohup make </dev/null & +.fi \fR +.P +.RE +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "Chapter 2" ", " "Shell Command Language", +.IR "\fIsh\fR\^" +.P +The Base Definitions volume of POSIX.1\(hy2008, +.IR "Chapter 8" ", " "Environment Variables" +.P +The System Interfaces volume of POSIX.1\(hy2008, +.IR "\fIsignal\fR\^(\|)" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, Copyright (C) 2013 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the +event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.unix.org/online.html . + +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |