Man Command
The man command is a fundamental utility in Unix-like operating systems, providing access to the system's reference manuals. It allows users to view documentation for commands, system calls, configuration files, and more. Understanding how to effectively use man is crucial for any developer or system administrator working with the command line.
Viewing Manual Pages
The most basic use of the man command is to display the manual page for a specific command. For example, to view the manual page for the bash shell:
man bashConverting Man Pages to PDF
You can convert man pages into PDF format for easier offline viewing or sharing. This is particularly useful for creating documentation archives or reports.
# To convert a man page to pdf:
man -t bash | ps2pdf - bash.pdfIn this command, man -t bash outputs the man page in a format suitable for typesetting (troff format), and then pipes it to ps2pdf, which converts PostScript to PDF.
Accessing Specific Manual Sections
Manual pages are organized into sections. For instance, section 7 often contains miscellaneous information, such as character sets.
# To view the ascii chart:
man 7 asciiViewing Configuration Files
While man primarily documents commands, you can sometimes find information about configuration files within their respective man pages. To directly view a configuration file, use a command like cat.
# To see config:
cat /private/etc/man.confSearching for Keywords in Man Pages
The man -k option (or its alias apropos) allows you to search for keywords across all available man page descriptions. This is invaluable when you know what you want to do but not the exact command name.
# To check the existence of a keyword in all of man pages:
man -k <keyword>For example, man -k network would list all man pages related to networking.