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RHCSA_Module1_BasicSystemManagementTasks Cheat Sheet (DRAFT) by

Module 1 of RHCSA including: Installing Redhat, Essential Tools, File Managment Tools

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Essential Commands

pwd
Show current working dir
whoami
Show current username
ls
List files in dir
ip addr show
Show current IP config
free -m
Show how much memory you have
df -h
Show available diskspace
cat /etc/hosts
Show contents of file
findmnt
Show mounted file system
 

Linux File System Hierarchy

Note
Highly standa­rdised, defined in FHS, maintained by Linux Founda­tion, starting point is root dir, other devices may be interg­rated in FHS using mounts
/
root dir, mounted on the name of device
/boot
Boot dir
/home
Home Dir
/var
Variables dir

Basic Permis­isons

  

Globbing

*
Any character
?
Only 1 character
[hm]
Either h or m
[!hm]
Neither h or m
[0=9][0-9]
Wildcard all 2 digit number

Regular Expres­sions

NOTE
Different than globbing (For file name), REGEX is for searching text pattern, best to use '', use with specific tools GREP,V­IM,­SED,AWK,
grep 'b.t'
Find pattern with b in first position, anything in second and t in third position
grep 'b.*t'
Pattern with b in the first, may or may not have 1 or many character and t in last postion
grep 'bo*t'
Pattern with b in first, may or may not have 'o' and t in last postion
grep 'b.?t'
No result, ? is part of extended REGEX, need to be used with EGREP
\<
Beginning of word
\>
End of word
{n}
Exactly n times