A glimpse at Unix Commands
Working in a terminal shell on a command line sounds like heaven for some developer, but hell for some others. Even though I would consider myself more technical than creative, i.e. more programmer than designer, it did quite happen a lot in the past that opening a terminal window (whether it was on Mac OSX or any other Unix-based machine) caused an attack of sweating. Well, I am exaggerating. But still, when I watched “the gurus” using the command line, I was always astonished how they could all keep all the myriads of commands and options in their heads. It is just a matter of practice and experience I guess. But if you don’t have that much of an experience, like I do, the following “cheat sheet” might help to get familiar with it and keep one or the other useful command in your head for the future.
Files and Directories
Change directory
cd [directory]
Examples
- cd ~ takes you to your users home directory
Resources
Create new directory
mkdir [dirname]
Examples
- mkdir homedir creates a new directory ‘homedir’
Resources
Delete a directory
rmdir [option] [directory]
Examples
- rmdir homedir remove the directory ‘homedir’
- rm -r directory remove a directory, even if files existed in that directory
Resources
Move file f to directory d
mv f1 [f2...] d
Examples
- mv myfile.txt newdirectory/ moves the file myfile.txt to the directory newdirectory
Resources
Rename directory d1 as d2
mv d1 d2
Examples
- mv alpha beta renames directory ‘alpha’ to ‘beta’
Resources
Delete a file
rm [-f] [-i] [-R] [-r] [filenames | directory]
Examples
- rm myfile.txt removes the file myfile.txt without prompting the user
- rm -rf /tmp/* removes all files (including write-protected ones) within /tmp recursively (including directories)
Resources
List contents of directory
ls [options] [pathnames]
Examples
- ls -a shows you all files, even files that are hidden (these files begin with a dot.)
- ls -d */ only list the directories in the current directory
- ls -lsa shows additional information about files (permission, size, hidden files, blocks etc.)
- ls -1 lists the contents with one entry on each line (without any add. info)
Resources
Create symbolic link
ln -s [destination] [source]
Examples
- ln -s ~/dev/myproject/htdocs . symlinks current directory to stated directory
Resources
Environment Information
Change password
passwd
Create command alias (csh/tcsh)
alias name1 name2
Create command alias (ksh/bash)
alias name1="name2"
Remove command alias na
unalias name1[na2...]
Login securely to remote node
ssh nd
End terminal session
exit
Set env var to value v (csh/tcsh)
setenv name v
set environment variable to value v (ksh/bash)
export name="v"
execute a file as a tcl script
source
Examples
- source ~/.profile executes .profile in user home directory
Search
Search for Text in Files
grep [options] PATTERN [FILE...]
Examples
- grep -r "class='headline'" /home/john/test searches for content “class=’headline’” in files
- grep -r "body" . searches for “body” in current directory
Search for Files
find [path] [expressions]
Examples
- find / -name "php.ini" searches for php.ini in the root and all subdirs
Resources
Process Control
Sleep for n seconds
sleep n
Print list of jobs
jobs
Kill job n
kill %
Print process status stats
ps
Remove process n
kill -9 n
Suspend background job n
stop %n
Display tasks
top
Run cmmd in background
cmmd&
Resume background job n
bg [%n]
Resume foreground job n
fg [%n]
Exit from shell
exit
Environment Status
Display command aliases
alias [name]
Print environment values
printenv [name]
Display disk quota
quota
Display the available disk space for each mount
df
Print date & time
date
List logged in users
who
Display current user
whoami
Output user information
finger [username]
Change finger information
chfn
Print working directory
pwd
Display recent commands
history
Submit recent command n
! n
Get current network adapter details (e.g. ip address)
ifconfig -a
File Manipulation
Vi fullscreen editor
vi [f]
Emacs fullscreen editor
emacs [f]
Text editor
ed [f]
Line, word, & char count
wc f
List contents of file
cat f
List file contents by screen
more f
Concatenates f1 & f2 into f3
cat f1 f2 >f3
Change protection mode of f
chmod mode f
Compare two files
cmp f1 f2
Copy file f1 into f2
cp f1 f2
Alphabetically sort f
sort f
Split f into n-line pieces
split [-n] f
Rename file f1 as f2
mv f1 f2
Delete (remove) file f
rm f
Outputs lines that match ptn
grep 'ptn' f
Lists file differences
diff f1 f2
Output beginning of f
head f
Output end of f
tail f
Examples
- tail -n 1000 /home/log/apache/error | grep index looks for “index” in the last 1000 lines of apache error log
Resources
