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