Renaming, Deleting, and Copying

Three commands every beginner should know are: cp,rm and mv. These are, respectively, copy, remove and move(rename). Here are their usages

cp oldFile newFile
rm garbageFile(s)
mv oldFile newFile

Warning! Pay heed before you proceed!

To clobber a file means to unlink it from your file system. When you clobber a file it is lost and there is virtually no chance you will recover its contents. There is no undelete facility as you might find on other computing systems you have used.

If you remove a file it is clobbered, and there is no way to get it back without an infinitude of horrid hassle. If you copy or rename onto an existing file, that file is clobbered, and it is gone forever. Always check to see if the file name you are copying or moving to is unoccupied! When in doubt, do an ls to look before you leap. All three of these commands have an option -i, which warns you before clobbering a file. Using this is a smart precaution.

The cp command copies oldFile to newFile. If newFile does not exist, it creates newFile; otherwise it will overwrite any existing newFile.

Try this at your UNIX prompt.

cp .bash_profile quack

Notice that the command cp has two arguments: the donor file and the recipient file. If you executed the last command successfully, you made a copy of your .bash_profile file to a file called quack.

Next, let’s get rid of all the animals in the zoo we had created before. The command rm will accept one or more arguments and remove the named files. We can accomplish this in one blow with

unix> rm aardvark buffalo cougar dingo elephant

Now enter

unix> ls -l

You will see that quack’s size is nonzero because it has a copy of the contents of your .bash_profile file in it. The file shown here has size 191. The size is the number of bytes contained in the file; yours may be larger or smaller. You will also see that the menagerie has been sent packing.

-rw-rw-r-- 1 morrison morrison     0 Jun  9 10:50 bar
-rw-rw-r-- 1 morrison morrison     0 Jun  9 10:49 foo
-rw-r--r-- 1 morrison morrison   191 Jun  9 11:25 quack
-rw-rw-r-- 1 morrison morrison     0 Jun  9 10:49 stuff

Let us now remove the file stuff. We are going to use the -i option. Enter this at the UNIX prompt.

unix> rm -i stuff

The system will then ask you if you are sure you want to remove the file. Tell it yes by typing the letter y. Be reminded that the -i option is also available with cp and mv. You should you use it to avoid costly mistakes.

Finally, we shall use mv This “moves” a file to have a new name. Let’s change the name of quack to honk and back again. To change quack to honk, proceed as follows.

unix> mv quack honk

Once you do this, list the files in long format. Then change it back.

Now you know how to copy, move, and create files. You can show them to the screen and you can list all the files you have. So far, we can create files two ways, we can create an empty file with touch or copy an existing file to a new file with cp.