SYS ADMIN Cheat Sheet

grep	searches text files for lines that match
chmod	changes a user's permissions
chown	change the owner
pwd	shows the full path name of the current working directory
head	displays the start of a text file
tail	displays the end of a text file
cat	displays the full text file
find	Searches files based on user criteria
mkdir	creates a directory
mv	movies a file or directory from one location to another
cp	copies a file or directory
wget	retrieves content from a web server
whoami	shows username
man	show the man pages of commands
wc	counts the number of lines words and characters
du	checks disk usage
rm	removes objects
vi	screen oriented text editor
nano	screen oriented text editor
touch	create a file
gzip	compress/decompress a file
ssh	used to remote log into a host
sudo	gives temporary root permissions
sort	lists files in a sorted order
rmdir	removes a directory
echo	moves data into a file
cd	change directory
ls	list the current directory

ifconfig	used to change IP and net mask
which	finds the direct path of what you pass to it
groupadd	adds a user group
dnf install	used to install libraries/packages
adduser	adds user
systemctl	used to manage a systemd service. (start/enable/restart/daemon-reload/etc)
journalctl	used to view system logs for systemd
pip3 install	used to install python modules
source activate	used to activate a virtual environment
firewall-cmd	provides an interface to manage runtime and permanent firewall configuration.
history	used to look at your previously input commands
mount	mounts file/directory (redirects folder path to another location)
unmount	umounts file/directory
locate	finds files based of of a database
su	used to change the current user
.(followed by filename)	Any file that begins with a “.” is hidden. “.” also can be used to reference the current working directory
ping	test the reachability of a host on an Internet Protocol network
netstat	displays network connections for Transmission Control Protocol
kill(Ctrl + C)	used to stop a running process
traceroute	displays the route and measures transit delays of packets across an Internet Protocol network
#!/bin/bash	used to denote a bash script
wget	retrieves content from web servers
scp	copies file from one host to another
exit	exits the current shell
clear	clears the terminal screen
ln	creates a symbolic link between two given arguments
xargs	executes commands from standard input
route	command used to view and manipulate the IP routing table

[[...]]	used to test in a bash script.
name=	used to assign a variable.
if /fi	marks the start and end of a if statement
elif	marks and else if statement in bash
Spaces in function calls represent different arguments
for ((i = 0 ; i < 100 ; i++));	one example of a bash for loop
$#	gets number of arguments
$*	gets all arguments
$1	gets the first argument
$@	gets all arguments starting from the first
for i in {1..5};	python style for loop
do / done	denotes what to do during a for loop and the end of a loop
while loop	loops while something is true
until loop	loops while something is false
return followed by a number is used for error return status
${name}	example of how to refer to a variable
“”	used to mark a section as a string
env	displays all environment variables
export	defines an environment variable
array=([0]=valA [1]=valB [2]=valC)	an example of how to instantiate an array
function name() {commands}	example of a bash functions
&&	and operator
\|\|	or operator
==	checks if a string equals another
!=	checks that string does not equal another
>	checks that string is greater than another
<	checks that string is less than another
-lt	less than for integers
-le	less than or equal for integers
-eq	equal for integers
-gt	greater than for integers
-ge	greater than or equal for integers
-ne	not equal for integers

git clone	clones a local or remote repository
git commit	commits current contents of the index and the given log message describing the changes.
git push	uploads local content to a remote repository
git status	gets the status of the git repository
df	shows disk usage
enable	enables and disables shell built-ins
-a file	file exists
-d file	file exists and is a directory
-e file	file exists; same -a
-f file	file exists and is a regular file
-r file	you have read permission
-s file	file exists and is not empty
-w file	you have write permission
-x file	you have execute permission on file
-N file	file was modified since it was last read
-O file	you own the file
-G file	file's group ID matches yours
yes	prints out an infinite loop with the given input
/	root directory
hostname	outputs the name of the current computer/server
write	sends a message to another user logged in to this computer
wall	broadcasts a message to all other users logged in to this computer
sleep	pause for a given number of seconds or ms
umask	change the default permissions given to newly created files
cal	outputs an ASCII calendar
date	outputs the current date/time
read	reads a value from standard input

SYS ADMIN Cheat Sheet (DRAFT) by ivese