Tags: unix, os x, linux, command line, terminal, bash, shell  
Date: 2013-08-20 23:09:02  

# Command line tutorial

To learn more, try the command line basics and UNIX tutorials found at [http://www.ee.surrey.ac.uk/Teaching/Unix/](http://www.ee.surrey.ac.uk/Teaching/Unix/) and [http://www.westwind.com/reference/OS-X/commandline/navigation.html](http://www.westwind.com/reference/OS-X/commandline/navigation.html).

## Requirements 

Open a command line shell: 

* use 'Terminal' on OS X or Linux
* use [cygwin](http://www.cygwin.com) on Windows (need to install first)


## Examples 

List files

	ls

Change directory

	cd Desktop

Change up one directory level

	cd ..

Print current directory location

	pwd	

Go to root of drive

	cd /

Go back to user home folder

	cd ~

Read in the Lord Of The Rings (LOTR) calendar with concatenate (should work on most Linux and Mac OS X systems):

	cat /usr/share/calendar/calendar.lotr

Read help for cat

	man cat

*Use `b` and `spacebar` to move forward and backwards a page at time when viewing man help pages. Press `q` to quit.*

Find all lines about 'Frodo' by **piping** the output from 'cat' into the 'grep' find program with the pipe operator `|`:  

	cat /usr/share/calendar/calendar.lotr | grep 'Frodo'
	
Same exact result as giving grep both original inputs:

	grep 'Frodo' /usr/share/calendar/calendar.lotr

Find all lines *ending* with 'Gandalf' using a 'regular expression' search pattern. To do this use the flag `-e` and the `$` in the search pattern to indicate the line ending position:  

	cat /usr/share/calendar/calendar.lotr | grep -e 'Gandalf$'

Save this output to a file on the Desktop. Notice the usage of both a pipe `|` and a redirection of output `>`:  

	cd ~/Desktop
	cat /usr/share/calendar/calendar.lotr | grep -e 'Gandalf$' > testfile.txt

Append something to the file using the redirection with append marker `>>`:  

	echo 'Double Rainbow!' >> testfile.txt



## Useful examples


### Print file usage 

List usage in human-readable format for a directory

	du -sh * 

### List file creation timestamps in seconds and filenames from ls command

	ls -lT *.tif | sort | awk '{ print $10, $8 }' > frametimes.txt
	find . -name '*.tif	' | xargs ls -lT | sort | awk '{ print $10, $8 }' | sed -Ee 's/^.\///g' > ~/Desktop/frametimes.txt

### List date times for .tif CCD movies for pasting into a spreadsheet

	ls -lTU *.tif | awk '{ print $6, $7, $8, $9}' > ~/Desktop/frametimes.txt   #U is file creation date-- file modification time might be better...
	ls -lT *.tif | awk '{ print $6, $7, $8, $9}' | pbcopy
	ls -lT *.tif | awk '{ print $10}' > ~/Desktop/frametimes.txt


### List filenames without pathnames

	ls -lT *.tif | awk '{ print $10}' | pbcopy  
	ls -lTU *.tif | awk '{ print $6, $7, $8, $9 }' > ~/Desktop/movietimes.txt


### Print tiff header information

	tiffutil -info filename.tif

### Copy files only less than 500MB in size

	rsync -av --max-size=500M FilePathToSource FilePathToDestination