nohup
User Commands nohup(1)NAME
nohup - run a command immune to hangupsSYNOPSIS
/usr/bin/nohup command [ argument ... ] /usr/xpg4/bin/nohup command [ argument ... ]DESCRIPTION
The nohup utility invokes the named command with the argu- ments supplied. When the command is invoked, nohup arranges for the SIGHUP signal to be ignored by the process. The nohup utility can be used when it is known that command will take a long time to run and the user wants to logout of the terminal; when a shell exits, the system sends its chil- dren SIGHUP signals, which by default cause them to be killed. All stopped, running, and background jobs will ignore SIGHUP and continue running, if their invocation is preceded by the nohup command or if the process programmati- cally has chosen to ignore SIGHUP. /usr/bin/nohup Processes run by /usr/bin/nohup are immune to SIGHUP (hangup) and SIGQUIT (quit) signals. /usr/xpg4/bin/nohup Processes run by /usr/xpg4/bin/nohup are immune to SIGHUP. The nohup utility does not arrange to make processes immune to a SIGTERM (terminate) signal, so unless they arrange to be immune to SIGTERM or the shell makes them immune to SIGTERM, they will receive it. If nohup.out is not writable in the current directory, out- put is redirected to $HOME/nohup.out. If a file is created, the file will have read and write permission (600, see chmod(1)). If the standard error is a terminal, it is redirected to the standard output, otherwise it is not redirected. The priority of the process run by nohup is not altered.OPERANDS
The following operands are supported: command The name of a command that is to be invoked. If the command operand names any of the special shell_builtins(1) utilities, the results are unde- fined. argument SunOS 5.8 Last change: 18 Mar 1997 1 User Commands nohup(1) Any string to be supplied as an argument when invoking the command operand. EXAMPLES Example 1: Applying nohup to pipelines or command lists It is frequently desirable to apply nohup to pipelines or lists of commands. This can be done only by placing pipe- lines and command lists in a single file, called a shell script. One can then issue: example$ nohup sh file and the nohup applies to everything in file. If the shell script file is to be executed often, then the need to type sh can be eliminated by giving file execute permission. Add an ampersand and the contents of file are run in the background with interrupts also ignored (see sh(1)): example$ nohup file & ENVIRONMENT VARIABLES See environ(5) for descriptions of the following environment variables that affect the execution of nohup: LC_CTYPE, LC_MESSAGES, PATH, and NLSPATH. HOME Determine the path name of the user's home directory: if the output file nohup.out cannot be created in the current directory, the nohup command will use the directory named by HOME to create the file. EXIT STATUS The following exit values are returned: 126 command was found but could not be invoked. 127 An error occurred in nohup, or command could not be found Otherwise, the exit values of nohup will be that of the com- mand operand.FILES
nohup.out the output file of the nohup execution if standard output is a terminal and if the current directory is writable. $HOME/nohup.out the output file of the nohup execution if standard output is a terminal and if the current directory is SunOS 5.8 Last change: 18 Mar 1997 2 User Commands nohup(1) not writable.ATTRIBUTES
See attributes(5) for descriptions of the following attri- butes: /usr/bin/nohup ____________________________________________________________ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | |_____________________________|_____________________________| | Availability | SUNWcsu | |_____________________________|_____________________________| | CSI | enabled | |_____________________________|_____________________________| /usr/xpg4/bin/nohup ____________________________________________________________ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | |_____________________________|_____________________________| | Availability | SUNWxcu4 | |_____________________________|_____________________________| | CSI | enabled | |_____________________________|_____________________________|SEE ALSO
batch(1), chmod(1), csh(1), ksh(1), nice(1), sh(1), shell_builtins(1), signal(3C), attributes(5), environ(5), XPG4(5) WARNINGS If you are running the Korn shell ( ksh(1)) as your login shell, and have nohup'ed jobs running when you attempt to logout, you will be warned with the message You have jobs running. You will then need to logout a second time to actually logout; however, your background jobs will continue to run.NOTES
The C-shell ( csh(1)) has a built-in command nohup that pro- vides immunity from SIGHUP, but does not redirect output to nohup.out. Commands executed with `&' are automatically immune to HUP signals while in the background. nohup does not recognize command sequences. In the case of the following command, SunOS 5.8 Last change: 18 Mar 1997 3 User Commands nohup(1) example$ nohup command1; command2 the nohup utility applies only to command1. The command, example$ nohup (command1; command2) is syntactically incorrect. SunOS 5.8 Last change: 18 Mar 1997 4