There are at least three ways to find files when you don't know their exact location:

* find

If you have a rough idea of the directory tree the file might be in (or even if you don't and you're prepared to wait a while) you can use find:

$ find directory -name targetfile -print

find will look for a file called targetfile in any part of the directory tree rooted at directory. targetfile can include wildcard characters. For example:

$ find /home -name *.txt -print 2>/dev/null

will search all user directories for any file ending in .txt and output any matching files (with a full absolute or relative path). Here the quotes () are necessary to avoid filename expansion, while the 2>/dev/null suppresses error messages (arising from errors such as not being able to read the contents of directories for which the user does not have the right permissions).

# grep (General Regular Expression Print)

$ grep options pattern files

grep searches the named files (or standard input if no files are named) for lines that match a given pattern. The default behaviour of grep is to print out the matching lines. For example:

$ grep hello *.txt

searches all text files in the current directory for lines containing hello. Some of the more useful options that grep provides are:
-c (print a count of the number of lines that match), -i (ignore case), -v (print out the lines that don't match the pattern) and -n (printout the line number before printing the matching line). So

$ grep -vi hello *.txt

searches all text files in the current directory for lines that do not contain any form of the word hello (e.g. Hello, HELLO, or hELlO).

If you want to search all files in an entire directory tree for a particular pattern, you can combine grep with find using backward single quotes to pass the output from find into grep. So

UNIX supports tools for accessing removable media such as CDROMs and floppy disks.

* mount, umount

The mount command serves to attach the filesystem found on some device to the filesystem tree. Conversely, the umount command will detach it again (it is very important to remember to do this when removing the floppy or CDROM). The file /etc/fstab contains a list of devices and the points at which they will be attached to the main filesystem:

$ cat /etc/fstab
/dev/fd0 /mnt/floppy auto rw,user,noauto 0 0
/dev/hdc /mnt/cdrom iso9660 ro,user,noauto 0 0

In this case, the mount point for the floppy drive is /mnt/floppy and the mount point for the CDROM is /mnt/cdrom. To access a floppy we can use:

$ mount /mnt/floppy
$ cd /mnt/floppy
$ ls (etc...)

To force all changed data to be written back to the floppy and to detach the floppy disk from...

The UNIX filesystem is laid out as a hierarchical tree structure which is anchored at a special top-level directory known as the root (designated by a slash '/'). Because of the tree structure, a directory can have many child directories, but only one parent directory. Fig. 2.1 illustrates this layout.


To specify a location in the directory hierarchy, we must specify a path through the tree. The path to a location can be defined by an absolute path from the root /, or as a relative path from the current working directory. To specify a path, each directory along the route from the source to the destination must be included in the path, with each directory in the sequence being separated by a slash. To help with the specification of relative paths, UNIX provides the shorthand . for the current directory and .. for the parent directory. For example, the absolute path to the directory play is /home/will/play, while the relative path to this directory from zeb is ../will/play.
...

UNIX systems usually support a number of utilities for backing up and compressing files. The most useful are:
tar (tape archiver)

tar backs up entire directories and files onto a tape device or (more commonly) into a single disk file known as an archive. An archive is a file that contains other files plus information about them, such as their filename, owner, timestamps, and access permissions. tar does not perform any compression by default.

To create a disk file tar archive, use

$ tar -cvf archivenamefilenames

where archivename will usually have a .tar extension. Here the c option means create, v means verbose (output filenames as they are archived), and f means file.To list the contents of a tar archive, use

$ tar -tvf archivename

To restore files from a tar archive, use

$ tar -xvf archivename


cpio
cpio is another facility for creating and reading archives. Unlike tar, cpio doesn't automatically...