CS 151 - Introduction to Data Structures

Lab 2

Unix

Using Unix

• cd
  Change Directory
  Example: cd cs151 (change to the directory cs151) (Note that this will not work if you do not have a cs151 directory.)
  Example: cd .. (change to the directory one above where you are, for instance is you are in /home/xena/cs151, then cd .. would put you in /home/xena
  Example: cd with no argument. This returns you to your home directory
• ls
  LiSt Files
  Display a list of all the files in the directory. It is very common to use the ls command immediately after cd.
  Example: ls list the files in the current directory
  Example: ls cs151 list the files in the directory cs151 (if it exists)
• mkdir
  MaKe DIRectory
  Create a directory
  Example: mkdir cs151 make a directory named cs151 Actually do this in your home directory. if you have not already done so. To be sure you are in your home directory enter the command cd (I often get back to my home directory when I mean to be somewhere else. Annoying, but at least then I know where I am)
• pwd
  Displays the current working directory. In other words this command shows you where you are.
• cp
  Copy a file
  Example cp a b make a copy of the file name "a" in the currect directory into a file named "b" in the current directory. Note that if "b" existed before the cp command, then it will be overwritten
  cp /home/gtowell/Public/151/L02/microtrades.txt m.txt make a copy of the file "microtrades.txt from the directory "/home/gtowell/Public/151/L02/" into the currect directory in a file named m.txt
  Lots of riffs on this general idea are possible with cp
• scp
  Secure copy a file
  The important difference between cp and scp is that you can use scp to copy between machines.
  Example scp UNIXLOGIN@MACHINEiD:a b make a copy of the file named "a" that is available on the machine MACHINEiDin the home directory of user UNIXLOGIN into a file named "b" in the current directory. Note that if "b" existed before the cp command, then it will be overwritten
  cp /home/gtowell/Public/151/L02/microtrades.txt m.txt make a copy of the file "microtrades.txt from the directory "/home/gtowell/Public/151/L02/" into the currect directory in a file named m.txt
  Example scp a UNIXLOGIN@MACHINEiD:b Make a copy of the file a in the current directory and put it in the home directory of UNIXLOGIN on MACHINEiD in the name b.
• mv
  Move (and/or) rename a file
  Example: mv a b rename the file named "a" to "b". As with cp, if there was a file nmed "b", it will be overwritten.
  mv /home/YOU/aa aa Move a file named "aa" from your home directory to the current directory and keep that file named "aa".
• rm
  remove a file
  Example: rm aa Permanently delete the file "aa"
• cat
  show the entire contents of a file to the terminal. ("cat" was originally an acronym for CAthode Ray Tube, which might give you a feel for how long this command has existed.)
  Example: cat aa the entrire contents of aa will show on the screen
• javac
  JAVA Compile
  Compile a java program.
  Example: javac HW.java
  This will compile the java code int he file HW.java. If there are no errors, it will create a file HW.class.
• java
  Run a java program.
  Example:java HW
  Run the java program named HW. This requires that the file HW.class is present in the current directory.

Lets finish this lab by copying files between your computer and the CS Unix computer. The command to copy between machines is scp. "scp" is "secure copy"; it basically extends the cp command so it can be used between machines.

First make a directory on your machine for this lab. The directory should be within the cs151 directory. (use cd and mkdir as needed).

Next, move into the diretcory you just made

Copy a file from Linux to your local directory. (Note that if you are doing this all from within linux you can use cp rather than scp (ask me))

	scp YOUR_CS_LOGIN@goldengate.cs.brynmawr.edu:/home/gtowell/Public/151/L02/microtrades.txt localmicro.txt

Edit the file using your favorite text editor (e.g. TextEdit on Mac, Notepad on Windows or you can use VSC). The major point here is just to find this file on your machine using a standard GUI tool.

Finally, copy this file back to Unix, but into your directory.

		scp localmicro.txt YOUR_CS_NAME@goldengate.cs.brynmawr.edu:cs151/lab02/remotemicro.txt
	

1. A completed table for the questions in the UNIX section