---
title: "Getting arguments passed to command"
description:
  "Investigative work of finding what argeuments where passed to the command
  after the fact."
canonical_url: "https://www.bigbinary.com/blog/getting-arguments-passed-to-command"
markdown_url: "https://www.bigbinary.com/blog/getting-arguments-passed-to-command.md"
---

# Getting arguments passed to command

Investigative work of finding what argeuments where passed to the command after
the fact.

- Author: Neeraj Singh
- Published: September 22, 2013
- Categories: Ruby

In [previous blog](do-not-allow-force-push-to-master) we discussed ruby code
where we used `ps -ocommand`. In this blog let's discuss how to get arguments
passed to a command.

## What is the issue

In the referred blog we are trying to find if `--force` or `-f` argument was
passed to the `git push` command.

The kernel knows the arguments that was passed to the command. So the only way
to find that answer would be to ask kernel what was the full command. The tool
to deal with such issues is `ps`.

In order to play with `ps` command let's write a simple ruby program first.

```plaintext
# sl.rb
puts Process.pid
puts Process.ppid
sleep 99999999
```

In terminal execute `ruby sl.rb`. In another terminal execute `ps`.

```plaintext
$ ps
  PID TTY           TIME CMD
82246 ttys000    0:00.51 -bash
87070 ttys000    0:00.04 ruby loop.rb a, b, c
82455 ttys001    0:00.40 -bash
```

So here I have two bash shell open in two different tabs in my terminal. First
terminal tab is running s1.rb. The second terminal tab is running `ps`. In the
second terminal we can see the arguments that were passed to program `s1`.

By default `ps` lists all the processes belonging to the user executing the
command and the processes started from the current terminal.

## Option -p

`ps -p87070` would show result only for the given process id.

```plaintext
$ ps -p 87070
  PID TTY           TIME CMD
87070 ttys000    0:00.04 ruby loop.rb a, b, c
```

We can pass more than on process id.

```plaintext
$ ps -o pid,command -p87070,82246
  PID COMMAND
82246 -bash
87070 ruby loop.rb a, b, c
```

## Option -o

`ps -o` can be used to select the attributes that we want to be shown. For
example I want only pids to be shown.

```plaintext
$ ps -o pid
  PID
82246
87070
82455
```

Now I want `pid` and `command`.

```plaintext
$ ps -o pid,command
  PID COMMAND
82246 -bash
87070 ruby loop.rb a, b, c
82455 -bash
```

I want result only for a certain process id.

```plaintext
$ ps -o command -p87070
COMMAND
ruby loop.rb a, b, c
```

Now we have the arguments that were passed to the command. This is the code that
article was talking about.

For the sake of completeness let's see a few more options.

## Option -e

`ps -e` would list all processes.

```plaintext
$ ps -e
  PID TTY           TIME CMD
    1 ??         2:56.20 /sbin/launchd
   11 ??         0:01.90 /usr/libexec/UserEventAgent (System)
   12 ??         0:02.11 /usr/libexec/kextd
   14 ??         0:09.00 /usr/sbin/notifyd
   15 ??         0:05.81 /usr/sbin/securityd -i
   ........................................
   ........................................
```

## Option -f

`ps -f` would list a lot more attributes including `ppid`.

```plaintext
$ ps -f
  UID   PID  PPID   C STIME   TTY           TIME CMD
  501 82246 82245   0  2:06PM ttys000    0:00.51 -bash
  501 87070 82246   0  4:54PM ttys000    0:00.04 ruby loop.rb a, b, c
  501 82455 82452   0  2:07PM ttys001    0:00.42 -bash
```

## Links

- [Human page](https://www.bigbinary.com/blog/getting-arguments-passed-to-command)