UNIX for Dummies Questions & Answers

can anyone explain me difference between tar and ufsdump commands.............and also i wd like to know the difference between incremental and differential backup.........

thx in advance

tar is used to create or extract an archives, a tar files always have .tar extension. you can extract from an archive tar file by
issuing tar xvf my_file.tar
and
you can create tar file by issuing

tar cvf my_newfile.tar archive_this_file

while ufsdump is used to backup all files or whole filesystem to a tape or another filesystem.
you use ufsdump to create a full backup or an incremental backup

to use ufsdump to create a full backup issue

ufsdump ucf 0 /dev/rmt/0 /usr

this will do a full backup of the /usr filesystem.

An incremental backup, back's up modify file only while differential is just another type of incremental backup.