5. Using Directories

5.1 Directories: Preliminary Notions

We have seen the differences between files under DOS/Win and Linux. As for directories, under DOS/Win the root directory is \, under Linux it is /. Similarly, nested directories are separated by \ under DOS/Win, by / under Linux. Example of file paths:

DOS:    C:\PAPERS\GEOLOGY\MID_EOC.TEX
Linux:  /home/guido/papers/geology/middle_eocene.tex

As usual, .. is the parent directory and . is the current directory. Remember that the system won't let you cd, rd, or md everywhere you want. Each user has his or her stuff in a directory called `home', given by the system administrator; for instance, on my PC my home dir is /home/guido.

5.2 Directories Permissions

Directories, too, have permissions. What we have seen in Section Permissions and Ownership applies to directories as well (user, group, and other). For a directory, rx means you can cd to that directory, and w means that you can delete a file in the directory (according to the file's permissions, of course), or the directory itself.

For example, to prevent other users from snooping in /home/guido/text:

$ chmod o-rwx /home/guido/text

5.3 Directories: Translating Commands

DIR:            ls, find, du
CD:             cd, pwd
MD:             mkdir
RD:             rmdir
DELTREE:        rm -rf
MOVE:           mv

Examples

DOS                                     Linux
---------------------------------------------------------------------

C:\GUIDO>DIR                            $ ls
C:\GUIDO>DIR FILE.TXT                   $ ls file.txt
C:\GUIDO>DIR *.H *.C                    $ ls *.h *.c
C:\GUIDO>DIR/P                          $ ls | more
C:\GUIDO>DIR/A                          $ ls -l
C:\GUIDO>DIR *.TMP /S                   $ find / -name "*.tmp"
C:\GUIDO>CD                             $ pwd
        n/a - see note                  $ cd
        ditto                           $ cd ~
        ditto                           $ cd ~/temp
C:\GUIDO>CD \OTHER                      $ cd /other
C:\GUIDO>CD ..\TEMP\TRASH               $ cd ../temp/trash
C:\GUIDO>MD NEWPROGS                    $ mkdir newprogs
C:\GUIDO>MOVE PROG ..                   $ mv prog ..
C:\GUIDO>MD \PROGS\TURBO                $ mkdir /progs/turbo
C:\GUIDO>DELTREE TEMP\TRASH             $ rm -rf temp/trash
C:\GUIDO>RD NEWPROGS                    $ rmdir newprogs
C:\GUIDO>RD \PROGS\TURBO                $ rmdir /progs/turbo

Notes:

• when using rmdir, the directory to remove must be empty. To delete a directory and all of its contents, use rm -rf (at your own risk).
• the character `~' is a shortcut for the name of your home directory. The commands cd or cd ~ will take you to your home directory from wherever you are; the command cd ~/tmp will take you to /home/your_home/tmp.
• cd - ``undoes'' the last cd.