We will always stumble across tools whose optional parameters we do not know from memory or tools we have never seen before. Therefore it is vital to know how we can help ourselves to get familiar with those tools. The first two ways are the man pages and the help functions.
It is always a good idea to familiarize ourselves with the tool we want to try first. We will also learn some possible tricks with some of the tools that we thought were not possible. In the man pages, we will find the detailed manuals with detailed explanations.
Syntax:
Animesh Roy@arishti[/lab]$ man <tool>
Let us have a look at an example:
Example:
Animesh Roy@arishti[/lab]$ man curl
curl(1) Curl Manual curl(1)
NAME
curl - transfer a URL
SYNOPSIS
curl [options] [URL...]
DESCRIPTION
curl is a tool to transfer data from or to a server, using one of the supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS,
IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, and TFTP). The command is designed to work without user interaction.
curl offers a busload of useful tricks like proxy support, user authentication, FTP upload, HTTP post, SSL connections, cookies, file transfer resume, Metalink, and more. As we will see below, the number of features will make our head spin!
curl is powered by libcurl for all transfer-related features. See libcurl(3) for details.
Manual page curl(1) line 1 (press h for help or q to quit)
After looking at some examples, we can also quickly look at the optional parameters without browsing through the complete documentation. We have several ways to do that.
Syntax:
Animesh Roy@arishti[/lab]$ <tool> --help
Example:
Animesh Roy@htb[/htb]$ curl --help
Usage: curl [options...] <url>
--abstract-unix-socket <path> Connect via abstract Unix domain socket
--anyauth Pick any authentication method
-a, --append Append to target file when uploading
--basic Use HTTP Basic Authentication
--cacert <file> CA certificate to verify peer against
--capath <dir> CA directory to verify peer against
-E, --cert <certificate[:password]> Client certificate file and password
<SNIP>
You can also use the short version of it:
Syntax:
Animesh Roy@arishti[/lab]$ <tool> -h
Example:
Animesh Roy@arishti[/lab]$ curl -h
Usage: curl [options...] <url>
--abstract-unix-socket <path> Connect via abstract Unix domain socket
--anyauth Pick any authentication method
-a, --append Append to target file when uploading
--basic Use HTTP Basic Authentication
--cacert <file> CA certificate to verify peer against
--capath <dir> CA directory to verify peer against
-E, --cert <certificate[:password]> Client certificate file and password
<SNIP>
As we can see, the results from each other do not differ in this example. Another tool that can be useful in the beginning is apropos. Each manual page has a short description available within it. This tool searches the descriptions for instances of a given keyword.
Syntax:Example:
Animesh Roy@arishti[/lab]$ apropos sudo
sudo (8) - execute a command as another user
sudo.conf (5) - configuration for sudo front end
sudo_plugin (8) - Sudo Plugin API
sudo_root (8) - How to run administrative commands
sudoedit (8) - execute a command as another user
sudoers (5) - default sudo security policy plugin
sudoreplay (8) - replay sudo session logs
visudo (8) - edit the sudoers file
Another useful resource to get help if we have issues to understand a long command is: https://explainshell.com/ Previous Mark Complete & NextNext Cheat Sheet
