A quick Linux cheat sheet, for those handly little commands you use all the time but sometimes your brain freezes up and a quick reference would be good to have:
File Commands
ls -list directory
ls -al -formatted listing with hidden files
ls -ltr -formatted listing ordered by time
cd dir -change to directory
cd - -go to directory in previously
cd -go to home directory
pwd -show current directory path
mkdir dir -make directory dir
rm file -delete file
rm -r dir -delete directory dir
rm -f file -force remove file
rm -rf dir -force remove directory dir
cp file1 file2 -copy file1 to file2
cp -r dir1 dir2 -copy dir1 to dir2; create dir2 if it doesn’t exist
mv file1 file2 -rename/move file1 to file2 if file2 is an existing dir, moves file1
into dir file2
ln -s file link -create symbolic link link to file
touch file -create or update file
cat > file -places standard input into file
more file -output the contents of file
head file -output the first 10 lines of file
tail file -output the last 10 lines of file
tail -f file -output the contents of file as it grows, starting with the last 10 lines
Process Management
ps -display your currently active processes
top -display all running processes
kill pid -kill process id pid
killall proc -kill all processes named proc
bg -lists stopped or background jobs; resume a stopped job in the background
fg -brings the most recent job to foreground
fg n -brings job n to the foreground
File Permissions
chmod octal file -change the permissions of file to octal, which can be found separately for user, group, and world by adding:
● 4 – read (r)
● 2 – write (w)
● 1 – execute (x)
Examples:
chmod 777 -read, write, execute for all
chmod 755 -rwx for owner, rx for group and world For more options, see man chmod.
chown user:group file -change the owner and group for a file
SSH
ssh user@host -connect to host as user
ssh -p port user@host -connect to host on port port as user
ssh-copy-id user@host -add your key to host for user to enable a keyed or passwordless login
Searching
grep pattern files -search for pattern in files
grep -r pattern dir -search recursively for pattern in dir
command | grep pattern -search for pattern in the output of command
locate file -find all instances of file
find . file -find file within current directory
find / file -find file within whole system
System Info
date -show the current date and time
cal -show this month’s calendar
uptime -show current uptime
w -display who is online
whoami -who you are logged in as
finger user -display information about user
uname -a -show kernel information
cat /proc/cpuinfo -cpu information
cat /proc/meminfo -memory information
man command -show the manual for command
df -show disk usage
du -show directory space usage
du -sk | sort -n -show sum of each directory space usage sorted by number in KB
free -show memory and swap usage
whereis app -show possible locations of app
which app -show which app will be run by default
Compression
tar cf file.tar files – create a tar named file.tar containing files
tar xf file.tar – extract the files from file.tar
tar czf file.tar.gz files – create a tar with Gzip compression
tar xzf file.tar.gz – extract a tar using Gzip
tar cjf file.tar.bz2 – create a tar with Bzip2 compression
tar xjf file.tar.bz2 – extract a tar using Bzip2
gzip file – compresses file and renames it to file.gz
gzip -d file.gz – decompresses file.gz back to file
Network
ping host – ping host and output results
whois domain – get whois information for domain
dig domain – get DNS information for domain
dig -x host – reverse lookup host
wget file – download file
wget -c file – continue a stopped download
Installation
Install from source:
./configure
make
make install
dpkg -i pkg.deb – install a package (Debian)
rpm -Uvh pkg.rpm – install a package (RPM)
Shortcuts
Ctrl+C – halts the current command
Ctrl+Z – stops the current command, resume with fg in the foreground
or bg in the background
Ctrl+D – log out of current session, similar to exit
Ctrl+W – erases one word in the current line
Ctrl+U – erases the whole line
Ctrl+R – type to bring up a recent command
!! - repeats the last command
exit – log out of current session
File Commands
ls -list directory
ls -al -formatted listing with hidden files
ls -ltr -formatted listing ordered by time
cd dir -change to directory
cd - -go to directory in previously
cd -go to home directory
pwd -show current directory path
mkdir dir -make directory dir
rm file -delete file
rm -r dir -delete directory dir
rm -f file -force remove file
rm -rf dir -force remove directory dir
cp file1 file2 -copy file1 to file2
cp -r dir1 dir2 -copy dir1 to dir2; create dir2 if it doesn’t exist
mv file1 file2 -rename/move file1 to file2 if file2 is an existing dir, moves file1
into dir file2
ln -s file link -create symbolic link link to file
touch file -create or update file
cat > file -places standard input into file
more file -output the contents of file
head file -output the first 10 lines of file
tail file -output the last 10 lines of file
tail -f file -output the contents of file as it grows, starting with the last 10 lines
Process Management
ps -display your currently active processes
top -display all running processes
kill pid -kill process id pid
killall proc -kill all processes named proc
bg -lists stopped or background jobs; resume a stopped job in the background
fg -brings the most recent job to foreground
fg n -brings job n to the foreground
File Permissions
chmod octal file -change the permissions of file to octal, which can be found separately for user, group, and world by adding:
● 4 – read (r)
● 2 – write (w)
● 1 – execute (x)
Examples:
chmod 777 -read, write, execute for all
chmod 755 -rwx for owner, rx for group and world For more options, see man chmod.
chown user:group file -change the owner and group for a file
SSH
ssh user@host -connect to host as user
ssh -p port user@host -connect to host on port port as user
ssh-copy-id user@host -add your key to host for user to enable a keyed or passwordless login
Searching
grep pattern files -search for pattern in files
grep -r pattern dir -search recursively for pattern in dir
command | grep pattern -search for pattern in the output of command
locate file -find all instances of file
find . file -find file within current directory
find / file -find file within whole system
System Info
date -show the current date and time
cal -show this month’s calendar
uptime -show current uptime
w -display who is online
whoami -who you are logged in as
finger user -display information about user
uname -a -show kernel information
cat /proc/cpuinfo -cpu information
cat /proc/meminfo -memory information
man command -show the manual for command
df -show disk usage
du -show directory space usage
du -sk | sort -n -show sum of each directory space usage sorted by number in KB
free -show memory and swap usage
whereis app -show possible locations of app
which app -show which app will be run by default
Compression
tar cf file.tar files – create a tar named file.tar containing files
tar xf file.tar – extract the files from file.tar
tar czf file.tar.gz files – create a tar with Gzip compression
tar xzf file.tar.gz – extract a tar using Gzip
tar cjf file.tar.bz2 – create a tar with Bzip2 compression
tar xjf file.tar.bz2 – extract a tar using Bzip2
gzip file – compresses file and renames it to file.gz
gzip -d file.gz – decompresses file.gz back to file
Network
ping host – ping host and output results
whois domain – get whois information for domain
dig domain – get DNS information for domain
dig -x host – reverse lookup host
wget file – download file
wget -c file – continue a stopped download
Installation
Install from source:
./configure
make
make install
dpkg -i pkg.deb – install a package (Debian)
rpm -Uvh pkg.rpm – install a package (RPM)
Shortcuts
Ctrl+C – halts the current command
Ctrl+Z – stops the current command, resume with fg in the foreground
or bg in the background
Ctrl+D – log out of current session, similar to exit
Ctrl+W – erases one word in the current line
Ctrl+U – erases the whole line
Ctrl+R – type to bring up a recent command
!! - repeats the last command
exit – log out of current session
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