Unix/Linux Command Reference.com

File Commands

System Infols – directory listingls -al – formatted listing with hidden files
cd dir - change directory to dir
cd – change to home
pwd – show current directory
mkdir dir – create a directory dir
rm file – delete filerm -r dir – delete directory dir
rm -f file – force remove filerm -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 or move file1 to file2
if file2 is an existing directory, moves file1 into
directory file2
ln -s file link – create symbolic link link to file
touch file – create or update filecat > file – places standard input into file
more file – output the contents of filehead file – output the first 10 lines of filetail file – output the last 10 lines of filetail -f file – output the contents of file as it
grows, starting with the last 10 lines

date – show the current date and timecal – 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
free – show memory and swap usage
whereis app – show possible locations of app
which app – show which app will be run by default

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 astopped job in the backgroundfg – brings the most recent job to foregroundfg n – brings job n to the foreground

File Permissions
chmod octal file – change the permissions of fileto 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.

SSH
ssh user@host – connect to host as userssh -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

SearchingCompression
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 tofile.gz
gzip -d file.gz – decompresses file.gz back to
file

Networkping 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 hostwget file – download file
wget -c file – continue a stopped download

Installation

Install from source:./configure
makemake 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 withfg 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 commandexit – log out of current sessiongrep pattern files – search for pattern in files
grep -r pattern dir – search recursively forpattern in dir
command | grep pattern – search for pattern in theoutput of command* use with extreme caution.
locate file – find all instances of file