CSC128 : Introduction to UNIX

Using tar

The tar Utility

tar
Manages archives of files.

tar -cvf filename.tar files...
This will create a tar file named filename.tar that contains all the files listed (files... ).

tar -xvf filename.tar
This will extract the files in  filename.tar

gzip
Compresses and decompresses single files.

gzip filename
This will compress the file called filename into a file called filename.gz

gzip -d filename.gz
gunzip filename.gz
Each of these commands will decompress the file called filename.gz into a file called filename

tar and gzip together

tar and gzip are often used in combination.  First, a series of files (often a whole directory tree) is tar 'ed, and then that tar file is gzipped, to take up less space.

user@machine:~ $ tar -cvf archive.tar ~user/mydir/ user@machine:~ $ gzip archive.tar user@machine:~ $ ls archive.tar.gz  mydir user@machine:~ $

These can be combined with pipes to perform the archiving and compression in one step:

tar -cvf - files | gzip > archive.tar.gz

Some newer versions of tar have a -z option, that will perform the gzip compression for you:

tar -czvf archive.tar.gz files

And to decompress:

gzip -dc archive.tar.gz | tar -xvf -

Or, with the newer versions of  tar :

tar -xzvf archive.tar.gz

dump
Selectively backs up the filesystem  (usually to a dumpfile).


restore
Restores a filesystem from a backup (usually a dumpfile).


uniq
Removes duplicate lines:

user@machine:~ $ cat names.txt David Angie John David Catherine Suzanne user@machine:~ $ sort names.txt Angie Catherine David David John Suzanne user@machine:~ $ sort names.txt | uniq Angie Catherine David John Suzanne user@machine:~ $

wc
Displays on stdout the number of lines, words, and characters in files .

user@machine:~ $ wc poem     537    5832   31416 poem user@machine:~ $