review tar

 

these two days I spent some time reading the manual of GNU tar (not BSD version, through my mac's shell is BSD), and get some usefull insights about tar:

1. tar is just a archiving tools , which means you can put many files together for the convinent of other operation.  8 operations are provided , which are Arctudx, and tons of options are provided

2. when you want to archieve files , use  tar -cf new_file.tar file1 file2 filen , when you want to compress files after archive , add option z (for gzip compress) or j( for bzip2 compress), when you want to compress but not archieve , close this website and go for manual of gzip or bzip or pbzip2.......

3. when you want to extrace files, use tar -xf new_file.tar , when you want to extract files which is compressed , add z or j option or do nothing

4. you can use A operation to cancatate two tar files, tar -Af file1.tar file2.tar

5. and use -r operation to append a fs file to a tar file,  tar -rf file1.tar normalize_file.xxx

6. want to know the content of the tar file ? just tar -tf new.tar 

7. -u, --update, only append files that are newer than the existing in archive, so if you want to refresh a file , delete it and append it again, use

    tar uf new.tar 1.txt 2.txt 3.txt to update a file , use tar df new.tar 2.txt to delete a file

here is the eight operations 

options are like backup (--backup, --suffix), overwrite or keep (-k for keep old files), exclude some pattern( --exclude)  or other , just query manual when you need use it 

now, you can use tar to copy a whole directory to another place ' cd sourcedir ; tar cf - . | (cd destdir ; tar xf -)'

ps: some pictures about different compress ways