20151204-2 选题

2024-12-26 21:30:55 +08:00 · 2015-12-04 15:56:20 +08:00 · 2015-12-04 15:56:20 +08:00 · 09a694c649
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+Linux / Unix: jobs Command Examples
+================================================================================
+I am new Linux and Unix user. How do I show the active jobs on Linux or Unix-like systems using BASH/KSH/TCSH or POSIX based shell? How can I display status of jobs in the current session on Unix/Linux?
+
+Job control is nothing but the ability to stop/suspend the execution of processes (command) and continue/resume their execution as per your requirements. This is done using your operating system and shell such as bash/ksh or POSIX shell.
+
+You shell keeps a table of currently executing jobs and can be displayed with jobs command.
+
+### Purpose ###
+
+> Displays status of jobs in the current shell session.
+
+### Syntax ###
+
+The basic syntax is as follows:
+
+    jobs
+
+OR
+
+    jobs jobID
+
+OR
+
+    jobs [options] jobID
+
+### Starting few jobs for demonstration purpose ###
+
+Before you start using jobs command, you need to start couple of jobs on your system. Type the following commands to start jobs:
+
+    ## Start xeyes, calculator, and gedit text editor ###
+    xeyes &
+    gnome-calculator &
+    gedit fetch-stock-prices.py &
+
+Finally, run ping command in foreground:
+
+    ping www.cyberciti.biz
+
+To suspend ping command job hit the **Ctrl-Z** key sequence.
+
+### jobs command examples ###
+
+To display the status of jobs in the current shell, enter:
+
+    $ jobs
+
+Sample outputs:
+
+    [1]   7895 Running                 gpass &
+    [2]   7906 Running                 gnome-calculator &
+    [3]-  7910 Running                 gedit fetch-stock-prices.py &
+    [4]+  7946 Stopped                 ping cyberciti.biz
+
+To display the process ID or jobs for the job whose name begins with "p," enter:
+
+    $ jobs -p %p
+
+OR
+
+    $ jobs %p
+
+Sample outputs:
+
+    [4]-  Stopped                 ping cyberciti.biz
+
+The character % introduces a job specification. In this example, you are using the string whose name begins with suspended command such as %ping.
+
+### How do I show process IDs in addition to the normal information? ###
+
+Pass the -l(lowercase L) option to jobs command for more information about each job listed, run:
+
+    $ jobs -l
+
+Sample outputs:
+
+![Fig.01: Displaying the status of jobs in the shell](http://s0.cyberciti.org/uploads/faq/2013/02/jobs-command-output.jpg)
+Fig.01: Displaying the status of jobs in the shell
+
+### How do I list only processes that have changed status since the last notification? ###
+
+First, start a new job as follows:
+
+    $ sleep 100 &
+
+Now, only show jobs that have stopped or exited since last notified, type:
+
+    $ jobs -n
+
+Sample outputs:
+
+    [5]-  Running                 sleep 100 &
+
+### Display lists process IDs (PIDs) only ###
+
+Pass the -p option to jobs command to display PIDs only:
+
+    $ jobs -p
+
+Sample outputs:
+
+    7895
+    7906
+    7910
+    7946
+    7949
+
+### How do I display only running jobs? ###
+
+Pass the -r option to jobs command to display only running jobs only, type:
+
+    $ jobs -r
+
+Sample outputs:
+
+    [1]   Running                 gpass &
+    [2]   Running                 gnome-calculator &
+    [3]-  Running                 gedit fetch-stock-prices.py &
+
+### How do I display only jobs that have stopped? ###
+
+Pass the -s option to jobs command to display only stopped jobs only, type:
+
+    $ jobs -s
+
+Sample outputs:
+
+    [4]+  Stopped                 ping cyberciti.biz
+
+To resume the ping cyberciti.biz job by entering the following bg command:
+
+    $ bg %4
+
+### jobs command options ###
+
+From the [bash(1)][1] command man page:
+
+注：表格
+<table border="1">
+  <tbody>
+    <tr>
+      <td>Option</td>
+      <td>Description</td>
+    </tr>
+    <tr>
+      <td><kbd><strong>-l</strong></kbd></td>
+      <td>Show process id's in addition to the normal information.</td>
+    </tr>
+    <tr>
+      <td><kbd><strong>-p</strong></kbd></td>
+      <td>Show process id's only.</td>
+    </tr>
+    <tr>
+      <td><kbd><strong>-n</strong></kbd></td>
+      <td>Show only processes that have changed status since the last notification are printed.</td>
+    </tr>
+    <tr>
+      <td><kbd><strong>-r</strong></kbd></td>
+      <td>Restrict output to running jobs only.</td>
+    </tr>
+    <tr>
+      <td><kbd><strong>-s</strong></kbd></td>
+      <td>Restrict output to stopped jobs only.</td>
+    </tr>
+    <tr>
+      <td><kbd><strong>-x</strong></kbd></td>
+      <td>COMMAND is run after all job specifications that appear in ARGS have been replaced with the process ID of that job's process group leader./td&gt;</td>
+    </tr>
+  </tbody>
+</table>
+
+### A note about /usr/bin/jobs and shell builtin ###
+
+Type the following type command to find out whether jobs is part of shell, external command or both:
+
+    $ type -a jobs
+
+Sample outputs:
+
+    jobs is a shell builtin
+    jobs is /usr/bin/jobs
+
+In almost all cases you need to use the jobs command that is implemented as a BASH/KSH/POSIX shell built-in. The /usr/bin/jobs command can not be used in the current shell. The /usr/bin/jobs command operates in a different environment and does not share the parent bash/ksh's shells understanding of jobs.
+
+--------------------------------------------------------------------------------
+
+via: 
+
+作者：Vivek Gite
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[1]:http://www.manpager.com/linux/man1/bash.1.html