CS 497C – Introduction to UNIX Lecture 13: - The File System

1. CS 497C – Introduction to UNIXLecture 13: - The File System Chin-Chih Changchang@cs.twsu.edu

2. 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.

3. 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.

4. 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.

5. 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 *

6. 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.

7. 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.

8. 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

9. 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.

10. 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.

11. 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.

12. 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

13. 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

14. 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.