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JOBS(P) JOBS(P)
NAME
jobs - display status of jobs in the current session
SYNOPSIS
jobs [-l| -p][job_id...]
DESCRIPTION
The jobs utility shall display the status of jobs that were started in the current
shell environment; see Shell Execution Environment .
When jobs reports the termination status of a job, the shell shall remove its pro-
cess ID from the list of those "known in the current shell execution environmentββ;
see Asynchronous Lists .
OPTIONS
The jobs utility shall conform to the Base Definitions volume of
IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
-l (The letter ell.) Provide more information about each job listed. This
information shall include the job number, current job, process group ID,
state, and the command that formed the job.
-p Display only the process IDs for the process group leaders of the selected
jobs.
By default, the jobs utility shall display the status of all stopped jobs, running
background jobs and all jobs whose status has changed and have not been reported by
the shell.
OPERANDS
The following operand shall be supported:
job_id Specifies the jobs for which the status is to be displayed. If no job_id is
given, the status information for all jobs shall be displayed. The format of
job_id is described in the Base Definitions volume of IEEE Std 1003.1-2001,
Section 3.203, Job Control Job ID.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of jobs:
LANG Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of IEEE Std 1003.1-2001,
Section 8.2, Internationalization Variables for the precedence of interna-
tionalization variables used to determine the values of locale categories.)
LC_ALL If set to a non-empty string value, override the values of all the other
internationalization variables.
LC_CTYPE
Determine the locale for the interpretation of sequences of bytes of text
data as characters (for example, single-byte as opposed to multi-byte char-
acters in arguments).
LC_MESSAGES
Determine the locale that should be used to affect the format and contents
of diagnostic messages written to standard error and informative messages
written to standard output.
NLSPATH
Determine the location of message catalogs for the processing of LC_MESSAGES
.
ASYNCHRONOUS EVENTS
Default.
STDOUT
If the -p option is specified, the output shall consist of one line for each pro-
cess ID:
"%d\n", <process ID>
Otherwise, if the -l option is not specified, the output shall be a series of lines
of the form:
"[%d] %c %s %s\n", <job-number>, <current>, <state>, <command>
where the fields shall be as follows:
<current>
The character ββ+ββ identifies the job that would be used as a default for the
fg or bg utilities; this job can also be specified using the job_id %+ or
"%%" . The character ββ-ββ identifies the job that would become the default if
the current default job were to exit; this job can also be specified using
the job_id %-. For other jobs, this field is a <space>. At most one job can
be identified with ββ+ββ and at most one job can be identified with ββ-ββ . If
there is any suspended job, then the current job shall be a suspended job.
If there are at least two suspended jobs, then the previous job also shall
be a suspended job.
<job-number>
A number that can be used to identify the process group to the wait, fg, bg,
and kill utilities. Using these utilities, the job can be identified by pre-
fixing the job number with ββ%ββ .
<state>
One of the following strings (in the POSIX locale):
Running
Indicates that the job has not been suspended by a signal and has not
exited.
Done
Indicates that the job completed and returned exit status zero.
Done(code)
Indicates that the job completed normally and that it exited with the speci-
fied non-zero exit status, code, expressed as a decimal number.
Stopped
Indicates that the job was suspended by the SIGTSTP signal.
Stopped (SIGTSTP)
Indicates that the job was suspended by the SIGTSTP signal.
Stopped (SIGSTOP)
Indicates that the job was suspended by the SIGSTOP signal.
Stopped (SIGTTIN)
Indicates that the job was suspended by the SIGTTIN signal.
Stopped (SIGTTOU)
Indicates that the job was suspended by the SIGTTOU signal.
The implementation may substitute the string Suspended in place of Stopped. If the
job was terminated by a signal, the format of <state> is unspecified, but it shall
be visibly distinct from all of the other <state> formats shown here and shall
indicate the name or description of the signal causing the termination.
<command>
The associated command that was given to the shell.
If the -l option is specified, a field containing the process group ID shall be
inserted before the <state> field. Also, more processes in a process group may be
output on separate lines, using only the process ID and <command> fields.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
The -p option is the only portable way to find out the process group of a job
because different implementations have different strategies for defining the pro-
cess group of the job. Usage such as $( jobs -p) provides a way of referring to the
process group of the job in an implementation-independent way.
The jobs utility does not work as expected when it is operating in its own utility
execution environment because that environment has no applicable jobs to manipu-
late. See the APPLICATION USAGE section for bg . For this reason, jobs is generally
implemented as a shell regular built-in.
EXAMPLES
None.
RATIONALE
Both "%%" and "%+" are used to refer to the current job. Both forms are of equal
validity-the "%%" mirroring "$$" and "%+" mirroring the output of jobs. Both forms
reflect historical practice of the KornShell and the C shell with job control.
The job control features provided by bg, fg, and jobs are based on the KornShell.
The standard developers examined the characteristics of the C shell versions of
these utilities and found that differences exist. Despite widespread use of the C
shell, the KornShell versions were selected for this volume of IEEE Std 1003.1-2001
to maintain a degree of uniformity with the rest of the KornShell features selected
(such as the very popular command line editing features).
The jobs utility is not dependent on the job control option, as are the seemingly
related bg and fg utilities because jobs is useful for examining background jobs,
regardless of the condition of job control. When the user has invoked a set +m
command and job control has been turned off, jobs can still be used to examine the
background jobs associated with that current session. Similarly, kill can then be
used to kill background jobs with kill% <background job number>.
The output for terminated jobs is left unspecified to accommodate various histori-
cal systems. The following formats have been witnessed:
1. Killed( signal name)
2. signal name
3. signal name( coredump)
4. signal description- core dumped
Most users should be able to understand these formats, although it means that
applications have trouble parsing them.
The calculation of job IDs was not described since this would suggest an implemen-
tation, which may impose unnecessary restrictions.
In an early proposal, a -n option was included to "Display the status of jobs that
have changed, exited, or stopped since the last status report". It was removed
because the shell always writes any changed status of jobs before each prompt.
FUTURE DIRECTIONS
None.
SEE ALSO
Shell Execution Environment , bg , fg , kill() , wait()
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating
System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C)
2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The
Open Group. 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.opengroup.org/unix/online.html .
POSIX 2003 JOBS(P)
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