55 lines
2.3 KiB
Markdown
55 lines
2.3 KiB
Markdown
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# The `ps` command
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The `ps` command is used to identify programs and processes that are running on the system and the resources they are using.
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Its frequently [pipelined](<https://en.wikipedia.org/wiki/Pipeline_(Unix)>) with other commands like `grep` to search for a program/process or `less`
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so that the user can analyze the output one page at a time.
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Let's say you have a program like openshot which is notorious for hogging system resources when exporting a video, and you want to close it, but the GUI has become unresponsive.
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### Example
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1. You want to find the PID of openshot and kill it.
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```
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ps aux | grep openshot
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kill - <openshot PID>
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```
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2. To Show all the running processes:
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```
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ps -A
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```
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### Syntax
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`ps [options]`
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When run without any options, it's useless and will print: `CMD` - the executable processes/(program) running, their `PID` - process ID, `TTY` - terminal type and `Time` - How long the process has utilized the CPU or thread.
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### Common Option
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If you are going to remember only one thing from this page let it be these three letter `aux`:
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`a` - which displays all processes running, including those being run by other users.
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`u` - which shows the effective user of a process, i.e. the person whose file access permissions are used by the process.
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`x` - which shows processes that do not have a `TTY` associated with them.
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### Additional Options:
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|**Option** |**Description** |
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|:---|:---|
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|`a`|Shows list all processes with a terminal (tty)|
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|`-A`|Lists all processes. Identical to `-e`|
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|`-a`|Shows all processes except both session leaders and processes not associated with a terminal|
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|`-d`|Select all processes except session leaders|
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|`--deselect`|Shows all processes except those that fulfill the specified conditions. Identical to `-N`|
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|`-e`|Lists all processes. Identical to `-A`|
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|`-N`|Shows all processes except those that fulfill the specified conditions. Identical to `-deselect`|
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|`T`|Select all processes associated with this terminal. Identical to the `-t` option without any argument|
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|`r`|Restrict the selection to only running processes|
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|`--help simple`|Shows all the basic options|
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|`--help all`|Shows every available options|
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Another useful command which give a realtime snapshot of the processes and the resources they are using about every ten seconds is `top`.
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