CS 497C - Introduction to UNIX
Lecture 13: - The File System
Chin-Chih Chang chang@cs.twsu.edu

mv: Moving or Renaming Files
* mv renames (moves) files and directories.
* It has two functions:
 - Rename a file (or directory).
 - Move a group of files to a different directory.
* Like cp, a group of files can be moved to a directory.
* mv can also be used to rename a directory.
* There is a -i (interactive) option available with mv.

cat: Displaying and Creating Files
* The cat command is the universal file viewer.
* cat is normally used for displaying text files only. Executables, when 
  seen with cat, simply display junk.
* If you have nonprinting ASCII characters in your input, you can use 
  cat with the -v option to display these characters.
* You can also cat to create a file.

cat: Displaying and Creating Files
* Enter the command cat, follow it with > and the filename foo:
$ cat > foo
A > symbol following the command means 
that the output goes to the filename 
following it.
[Ctrl-d]
* The [Ctrl-d] is used to end the session of all commands that accept 
  input from keyboard.

file: Know the File Types
* The file command tells not only the file types (ordinary, directory, 
  and device) but also more information about these files.
$ file semaphore.c
semaphore.c     C program text
$ file *

lp and cancel: Printing a File
* A user has to spool (or line up) a job along with others in a print 
  queue.
* The spooling facility in System V is provided by the lp 
  (line printing) command.
lp chap01
* The -d (destination) option with the printer name identifies which 
  printer is used.
* The -t (title) option prints the title on the first page.

lp and cancel: Printing a File
* The -m (mail) option is used to notify the user after the file has 
  been printed.
* You can print more than one copy by using -n option.
lp -dlaser chap01
lp -n3 -m chap01
* Jobs queued by lp are canceled with the cancel command.

Printing with lpr, lpq, and lprm
* Linux uses Berkeley's printing system which supports the lpr command 
  for printing and lprm for removing jobs.
* To know the number of the job, use the lpq command.
$ lpr typescript
$ lpq
$ lprm 17

df: Finding Out the Free Disk Space
* The df command finds out the free disk space.
* It shows how many blocks (usually 512 bytes) of disk space and inodes 
  (files) are free for use.
* The -t (total) option includes the total amount of disk space in each 
  file system.

du: Finding Out Your Own Consumption
* The du (disk usage) command reports disk usage by a recursive 
  examination of the directory tree.
du .
* The -s (summary) summarizes the disk usage.

Compress, gzip, and zip: Compress Your Files
* For disk space conservation or the fast download, files are frequently 
  compressed.
* The most frequently used compression programs in UNIX are compress, 
  gzip, and zip.
* The compress command produces the file with Z extension.

Compress, gzip, and zip: Compress Your Files
compress daily.log
uncompress daily.log.Z
* You can use the zcat command to uncompress a file and see its contents. 
A compressed gzip file has the extension .gz.
* It is decompressed with the gunzip command.
gzip sales.dbf
gunzip sales.dbf.gz

Compress, gzip, and zip: Compress Your Files
* gzip today is a standard compression utility on the Internet.
* Phil Katz's pkzip program compresses multiple files into an archive (a 
  single file containing a group of files).
zip fin *.html
* With the -r option, zip can also recursively compress an entire 
  directory.
zip -r zipdir docs

Compress, gzip, and zip: Compress Your Files
* On the Internet, you'll see these extensions: 
 - zip - These are files compressed with zip.
 - tar - Files archived into a single file with the UNIX tar command.
 - gz - These are compressed with gzip.
 - tar.Z - Files archived into a single file with tar and then 
   compressed with compress.
 - tar.gz - Files archived into a single file with tar and then 
   compressed with gzip.