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 process ID from the list of those "known
in the current shell execution environment’’; see Asynchronous
Lists .
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.
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.
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 internationalization 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 characters 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
.
The character ’+’ 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 ’-’
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 ’+’ and at most
one job can be identified with ’-’ . 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 prefixing the job number
with ’%’ .
<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 specified 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.
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 process 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 manipulate. See the APPLICATION
USAGE section for bg . For this
reason, jobs is generally implemented as a shell regular built-in.
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 historical 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 implementation, 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.
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 .
IEEE/The Open Group
JOBS (P)
2003
Generated by OpenAsthra.com from man1p/jobs.1p using man macros.
