WAYTOGEEK.BLOGSPOT.COM: Unix/Linux Command Reference

Once again hello to all of my reader! I have collected some of the commands of Linux/Unix, what i have been using on my ubuntu from last few years.

File Commands

ls - directory listing
Is -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 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 or move file1 to file2 if file2 is an existing directory, moves file1 into directory file2
In -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.

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

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
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)

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