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Linux Commands

A Linux terminal commands list that's commonly used.

Navigation

Command	Description
pwd	Where am I?
ls	List files and directory.
ls -l	List files and directories in an extended form.
ls -lh	List files and directories in an extended form and shows the file's unit of measurement.
ls -a	List all files and directories including the hidden ones.
ls -ltr	List files and directories by date.
ls -la	List all files and directories including the hidden ones in an extended form.
cd <directory>	Change to destination directory
cd <directory>/<sub-directory>	Change to destination sub-directory.
cd ..	Go back to previous directory.
cd ../../	Go back to previous directory.
cd /	Go to root directory.
cd ~	Go to home directory.
(cd .. ;ls -l)	Execute the command in a "sub shell", in the case of the example, continue in the same directory, after listing the previous directory.
clear	Clear the terminal screen.
Ctrl + l	Clear the terminal screen.
exit	Close the terminal.
ctrl + c	Terminates an application currently running in the terminal

File and directory manipulation

Command	Description
mkdir <name>	Create a directory.
mkdir -p <a>/<ab>/<abc>	Create nested directories.
touch <file>	Create file.
mv <file> <destination>	Move file to destination directory.
mv <origin>/<file> .	Move file from origin to current directory.
mv <directory> <new name>	Rename directory.
mv <file> <new name>	Rename file.
cp <file> <new copy>	Copy file to a new file.
cp -r <directory> <new directory>	Copy directory to a new directory on a recursive way.
rm <file>	Remove file.
rm -r <directory>	Remove directory on a recursive way.
cat <file>	Shows the file contents.
more <file>	Shows the file contents. Load all file on memory at one go.
less <file>	Shows the file contents. Load the file using streams, this means that the command load just the necessary part of file.(Can use vim's commands)
chown <user> <file>	Changes the user that's the file owner.
chown :<grupo> <file>	Changes the group of file owners. This command can be used together with the previus one.

Search for terms in files - GREP Command

Command	Description
grep <term> <file>	Fetch character pattern in file.
grep -i <term> <file>	Searches the character pattern in file, ignoring differences between upper and lower case.
grep -v <term> <file>	Searches for the inverse pattern of characters in file, returns the lines that do not conform to the pattern.
grep --color <term> <file>	Displays the pattern found in color.
grep -c <term> <file>	Returns the number of lines that match the pattern you are looking for.
grep -n <term> <file>	Displays next to the pattern found the line number of the file where the pattern is found.
grep -w <term> <file>	Searches for the pattern of characters in file, returns only the lines where the pattern is in complete words.
grep -R <term>	Search the pattern in directories and files, recursively, hierarchically.
grep -R -l <term>	Searches the pattern in directories and files, recursively, hierarchically, returning the name of the file containing the pattern you are looking for.
grep ^<term> <file>	Searches for the character pattern at the beginning of a line in file.
grep <term>$ <file>	Searches for the character pattern at the end of a line in file.
grep s.r <file>	Searches for the pattern letter s followed by any character followed by the letter r.
grep -w -E j.{1,}y <file>	Searches for words starting with the letter j and ending with y with 3 or more characters.
grep ^[aeiou] -i <file>	Search for lines beginning with lowercase and uppercase vowels in a file.
grep ^[1-5] <file>	Search for lines starting with 1,2,3,4 ou 5 in a file.
grep -E [aeiou]{2,3} <file>	Search for lines containing two or three joined vowels.
grep -E -i '(ch|x)[aeiou]	Searches for lines containing CH or X followed by vowels, ignoring upper and lower case.
grep -E Go{2,}gle	Search for G followed by 2 or more letters o. Recognizes Google Goooogle Gooooooooogle.
grep -E Go?gle	Search by letter G followed by 0 or 1 letter o. Recognizes Gogle Ggle.

Search files - Command LOCATE

Command	Description
locate <file>	Search for the file by name.
locate -b <file>	Search for the file by name, listing only the files that have the search term instead of returning directories that lead to the files.
locate -e <file>	Search for the file by name, and returns the entry of existing files at the time the Linux locate command is executed.
locate -q <file>	Search for the file by name, and disable the display of errors found in the search process.
locate -c <file>	Search for the file by name, and shows the number of matching files, instead of the file names.

History

Command	Description
history	Shows commands history.
Ctrl + r	Start the interactive search on history or find the next occurrence when the interactive search has already started.
!n	Execute the command number 'n'.
!!	Repeat the last command.
!<string>	Repeat the last command that starts with 'string'.
dirs -p	Shows the history of visited directories.

Permissions

Command	Description
chmod xxx <file or directory>	chmod changes the permissions of user, group or everyone to read, write or run the file.
chmod -R xxx <directory>	Changes the permissions of all files and directories that are in the directory recursively.

This command uses a string that represents the permissions.

• ( r ) read permitted.

• ( w ) write permitted.

• ( x ) execution permitted.

Exemples

Command	Description
chmod 111 <file>	Everyone could execute the file.
chmod 222 <file>	Everyone could write to the file.
chmod 700 <file>	Only the owner has all the permissions.
chmod 600 <file>	The owner could read and write the file.

Varieties

Command	Description
diff -qr <directory1> <directory2>	Shows the differences between the directories. Argument -q shows modified or nonexistent files. Argument -r shows the differences between files content.
man <command>	Page of Manual of commands.
whoami	Who am i? Shows you username.
whatis	Displays what a command is.
date	Displays date and time.
ps	Displays information about processes.
ps -aux	Displays information about processes, users, tty.
expr	Evaluate expressions.
sleep 1	Pauses execution for a certain time, in this case 1 second.
uname	Displays system information.
uname -r	Displays information about the kernel.
hostname	Displays or sets system hostname.
curl	Make web requests.
ping	Send ICMP requests.
netstat	Shows network connections, routing tables, interface statistics and masked connections.
wget	Download content from a web page.
ssh	OpenSSH SSH client (remote access).
base64	Base64 encodes / decodes the FILE, or standard input, to standard output.

Monitoring

Command	Description
htop	Displays processes running on the system.
vmstat	Information about processes, memory, paging, block I / O, traps, disks and CPU activity.
free	Watch and monitor system memory usage.
stat <file|directory>	Prints the given file or directory INode informations.

Packet manager (apt-get)

Command	Description
sudo apt-get install <package>	Installs a package.
sudo apt-get install -f	Finds and fixes broken packages.
sudo apt-get remove <package>	Removes a package. Leaves user configuration files.
sudo apt-get purge <package>	Removes a package completely.
sudo apt-get update	Verifies if exists packages repository updates.
sudo apt-get upgrade	Verifies if exists system updates.
sudo apt-get autoremove	Removes all obsolete and unnecessary packages.
sudo apt-get autoclean	Cleans the packet manager cache.
apt-cache search <search>	Finds packages in repository.
apt-cache show <name_of_package>	Shows a description about the package.