isecur1ty training center Presented by : Eng. Mohammad Khreesha

 Introduction  Getting help in Linux  man pages  apropos (man –k)  whatis  whereis  man sections  -h option  info

 The command line is the tool that all GUI applications use to do their work.  In other words: graphical tools are merely front-ends to command line tools.

 The basic Linux command works like this:  command [OPTIONS] [ARGUMENTS ] ▪ command: This is the base of the command. ▪ OPTIONS: Options are those pieces of the command that alter the behavior of the command. ▪ ARGUMENTS: Arguments are typically file names or other data that is needed by the command. ▪ Example:  mkdir -m 654 TEST (create the directory TEST with the mode 654 )

 This module will guide you to the correct way for getting help in Linux without searching on internet ….  We will discuss multiple ways to get help in linux…

 The man pages are a user manual that is by default built into most Linux distributions (i.e., versions) and most other Unix-like operating systems during installation. They provide extensive documentation about commands and other aspects of the system, including configuration files, system calls, library routines and the kernel …..  Examples:  man whois  man syslog.conf  man syslogd

 The apropos command displays a list of all topics in the man pages that are related to the subject of a query.  Examples:  man -k syslog or apropos syslog

 The whatis command provides very brief descriptions of command line programs and other topics related to Linux and other Unix- like operating systems.  Examples:  whatis cat or man –f cat

 whereis used to locate the binary, source, and manual page files for a command…  Examples:  whereis tar

 The manual is generally split into eight numbered sections, organized as follows :  Executable programs or shell commands  System calls (functions provided by the kernel)  Library calls (functions within program libraries)  Special files (usually found in /dev)  File formats and conventions eg /etc/passwd  Games  Miscellaneous (including macro packages and conventions), e.g. man(7)  System administration commands

 Examples :  man passwd : opens the first manual found  man 5 passwd : opens a page from section 5

 If you want to know more and more about man pages you can get help about man (manual) pages like this :  man man  Note : man pages don’t have answers for everything like : man hello

 Sometimes you may know the functionality of a command very well, but cannot recollect all the available options for a specific command. Use -h option of the command to review all available options of the command.  Examples : ▪ cat –help ▪ netstat -h

 Display a file’s help information in an alternate format.  Some programs don’t have man pages – or have very incomplete man pages – and store their documentation as info documents.  Examples:  info cat

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