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man -a useradd
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useradd command in all sections
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man -k passwd | grep 8
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searching passwd keyword in man page from section 8
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man 8 useradd
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showing useradd command from section 8
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man man
|
showing man command help
|
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ln /etc/hosts myhosts
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create hard links myhosts to /etc/hosts
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ln -s /etc/hosts/ myhosts
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create symbolic links myhosts
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find /etc -name hosts
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Find in /etc files with exact name "hosts"
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find /etc -name "hosts"
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Find in /etc files with "hosts" in its name
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find /etc -name "hosts" -exec cp {} /etc/test/ \;
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Find in /etc file with "hosts" in name and copy it to /etc/test
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find /etc -size +100K 2>/dev/null
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File in /etc files over 100Kb and send error to /dev/null
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grep student /etc/* 2>/dev/null
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Find in /etc files with "student" in content
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grep -l student /etc/* 2>/dev/null
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List only the directories
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find /etc -exec grep -l student {} \; 2>/dev/null; cp {} /find/contents/ \; 2>/dev/null
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Find all directories and sub with files containing student in content and copy the result to /find/content
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visudo
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Edit sudo configuration file
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chvt t
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Change virtual terminal 5
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/etc/securetty
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Secure console file, delete 1 will no longer have access to that console
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>
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overwrite
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<
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send into command
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>>
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append
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<<
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append into command or file
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2> /dev/null
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redirect error to null file
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cut -d : -f 3 /etc/passwd
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Display third column using ":" delimiter in /etc/passwd
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cut -d : -f 1 /etc/passwd | sort | tr [:lowercase:] [:uppercase:]
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Display all username in /etc/passwd and translate all lowercase to uppercase
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awk -F : ' { print $1 } ' /etc/passwd
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Display first column using ":" field delimiter (-F)
|
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sed -i -e '10d' grepfile1
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Delete (10d) interactively (-i) using edit option(-e) the tenth line
|
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tar cvf name.tar /dir
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Create name.tar file from /dir
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tar -xvfz archive.tar.gzip -C /target/dir
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Extract archive.tar.gzip to /tar/dir
|
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ls -al /etc
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list all files (-a) with all info (-l) in /etc
|
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ls -r
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list sub-directories (-r)
|
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cp -R /etc/hosts ~/files/
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copy all (-R) in hosts to home/files/
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mkdir -p /etc/photos
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make directory etc and sub-directory photos
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mv /tmp/test ~
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move test to home directory
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rm -rf
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remove recursively and ignore non existent file
|
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head -n 5 /etc/passwd
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Display first 5 lines in /etc/passwd
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tail -f /var/log/messages
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Display the recent system messages
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note
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Use with sed, vim, awk, grep
|
||
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^
|
Start of a string
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^abc
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abc, abcdef,abc123
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|
$
|
End of a string
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abc$
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abc,123abc,fdeabc
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|
|
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Alteration
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1|8
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1,8
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{...}
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Exact quanity
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ab{2}c
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abbc
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[...]
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Explicit set of character to match
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a[bB]c
|
abc,aBc
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*
|
Null or more of the preceding character
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ab*c
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ac,abc,abbbbc
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(...)
|
Group of character
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(123){3}
|
123123123
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+
|
One or more of predceding character
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ab+c
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abc,abbbbc
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?
|
Null or 1 of the preceding character
|
ab?c
|
abc, ac
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|
.
|
Any single character
|
||
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\s
|
Whitespaces
|
.*
|
Zero or more of any character
|
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
