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Now that you have a few files and a directory in your home directory we will use these to explore some simple UNIX commands that you will grow to know and love.
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An example session to demonstrate these commands follows:
% ls
junk.txt myfile.txt session1.txt stuff.txt
List all the files in the current directory, note that files beginning with a `.' are not listed. The -a option allows you to list, rather than hide, the entries starting with a `.' and the -l option allows you to use a long listing format, shown below.
% ls -al
total 20
drwx------ 2 cathy 4096 Jan 21 16:45 .
drwx------ 32 cathy 4096 Jan 21 16:39 ..
-rw------- 1 cathy 120 Jan 21 16:43 junk.txt
-rw------- 1 cathy 176 Jan 21 16:45 myfile.txt
-rw------- 1 cathy 0 Jan 21 16:45 session1.txt
-rw------- 1 cathy 75 Jan 21 16:40 stuff.txt
In this listing, all files are listed. The permissions of each file are listed along with information about the owner of the file, the size of the file and the date the file was last touched. Note that the listing for your account will probably show different files to those in this list.
% mkdir temp
% ls
junk.txt myfile.txt session1.txt stuff.txt temp
Now you have a directory called temp.
% ls -al
total 24
drwx------ 3 cathy 4096 Jan 21 16:46 .
drwx------ 32 cathy 4096 Jan 21 16:39 ..
-rw------- 1 cathy 120 Jan 21 16:43 junk.txt
-rw------- 1 cathy 176 Jan 21 16:45 myfile.txt
-rw------- 1 cathy 0 Jan 21 16:45 session1.txt
-rw------- 1 cathy 75 Jan 21 16:40 stuff.txt
drwx------ 2 cathy 4096 Jan 21 16:46 temp
Notice the permissions on the temp directory. The first character is a `d', indicating that this is a directory. The next three characters make up the owner's permissions. In this case the owner of temp has read, write and execute permissions to the temp directory, but permissions to group and other users is denied.
The permissions on the file junk.txt indicate that it is a file (as the first character in the permissions list is blank). The owner of the file has read and write permissions to the file.
Change directory to the temp directory.
% cd temp
% ls -al
total 8
drwx------ 2 cathy 4096 Jan 21 16:46 .
drwx------ 3 cathy 4096 Jan 21 16:46 ..
Notice that this directory is empty (not surprisingly!). The directories listed here are `.' which is the current directory, and `..' which is the parent directory.
Change directory back up to the parent directory `..'.
% cd ..
Copy the file junk.txt to the temp directory.
% cp junk.txt temp
Change directory to temp.
% cd temp
% ls -al
total 12
drwx------ 2 cathy 4096 Jan 21 16:48 .
drwx------ 3 cathy 4096 Jan 21 16:46 ..
-rw------- 1 cathy 120 Jan 21 16:48 junk.txt
The temp directory contains a copy of the file junk.txt.
Now copy the file stuff.txt from the parent directory to the current directory, which is still temp. Remember that `..' is the parent directory, and `.' is the current directory.
% cp ../stuff.txt .
% ls
junk.txt stuff.txt
The directory temp now also contains a copy of the file stuff.txt.
Use the move command to rename the file junk.txt to other.txt.
% mv junk.txt other.txt
% ls
other.txt stuff.txt
The directory temp has the file other.txt now.
Use the mv command to move the file other.txt up to the parent directory.
% mv other.txt ../other.txt
Change directory up to the parent directory.
% cd ..
% ls
junk.txt other.txt stuff.txt
myfile.txt session1.txt temp
The parent directory now has the file other.txt.
Remove the file other.txt.
% rm other.txt
% ls
junk.txt myfile.txt session1.txt stuff.txt temp
The file other.txt has been removed.
Attempt to remove the temp directory.
Note that you are not able to remove a directory that is not empty.
% rmdir temp
rmdir: temp: Directory not empty
Use the recursive option of the remove command to remove the entire contents of the directory temp, and then remove the directory. (Be very careful with this option!)
% rm -rf temp
Change to the temp directory ...
% cd temp
Can't cd to temp: No such file or directory
...but as the directory no longer exists, you can't change to it.
% ls
junk.txt myfile.txt session1.txt stuff.txt
The temp directory is no longer listed.
Make a directory called letters.
% mkdir letters
% ls -al
total 24
drwx------ 3 cathy 4096 Jan 21 16:58 .
drwx------ 32 cathy 4096 Jan 21 16:39 ..
-rw------- 1 cathy 120 Jan 21 16:43 junk.txt
drwx------ 2 cathy 4096 Jan 21 16:58 letters
-rw------- 1 cathy 176 Jan 21 16:45 myfile.txt
-rw------- 1 cathy 0 Jan 21 16:45 session1.txt
-rw------- 1 cathy 75 Jan 21 16:40 stuff.txt
There is now an empty directory called letters.
Use the rmdir commands to remove the empty directory.
% rmdir letters
% ls -al
total 20
drwx------ 2 cathy 4096 Jan 21 16:58 .
drwx------ 32 cathy 4096 Jan 21 16:39 ..
-rw------- 1 cathy 120 Jan 21 16:43 junk.txt
-rw------- 1 cathy 176 Jan 21 16:45 myfile.txt
-rw------- 1 cathy 0 Jan 21 16:45 session1.txt
-rw------- 1 cathy 75 Jan 21 16:40 stuff.txt
The letters directory is no longer listed.
Loc Van Huynh 2007-03-15
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