Backing Up

• To back up data, it can be done simply with cp or with more robust tools like rsync

rsync

• Only copies files if they were modified
• Only copies modified part(very fast)
• Can be used to store in remote machines
• Using the -r flag, directories can be copied recursively

Recommended is for example

rsync --progress -avrxH  --delete sourcedir destdir

dd

• Can be used for copying raw disk data or making copies or raw disk space
• Is very powerful and should be used carefully

Compressing

Made in order to reduce filesize (disk and faster over network)

gzip

• Most used in linux
• Examples:

  gzip * #Compresses every file in the pwd. Same name + .gz
  gzip -r folder #Compresses everything in folder and adds it to folder.gz
  gunzip a #Decompresses a found in a.gz
  gzip -d a #Same as above
  

bzip2

• Produces smaller files than gzip but takes longer
• Used for big files
• Is now Deprecated, and xz should be used instead
• Examples

  bzip2 * #Every file in the pwd with the .bz2 extension
  bunzip2 a.bz2 #Decompresses a in a.bz2
  bzip2 -d *.bz2 #Same as above
  

xz

• Most space efficient compression utility used in Linux
• Used for kernel files
• Examples:

  xz * #Every file in the pwd, replaced with a .xz
  xz foo #Compresses foo into foo.xz and deletes foo if successful
  xz -dk foo.xz #Decompresses foo.xz and keeps the file
  

zip

• Not very used in Linux
• Used mostly when receiving/sending files to windows
• Examples

  zip backup * #All files in pwd into backup.zip
  zip -r backup.zip ~ #Stores home directory into backup.zip recursively
  unzip backup.zip #Extracts all files and puts them in pwd 
  

tar

• Using for putting together (or extracting) for archive files or “tarballs”
• Compressing/Decompressing can be done at the same time
• Examples:

  tar -xvf dir.tar #Extracts files from dir.tar into dir
  tar -zcvf mydir.tar.gz mydir #Create a tarball and compress it with gzip
  tar -jcvf mydir.tar.bz2 mydir #Create a tarball and compress it with bz2
  tar -Jcvf mydir.tar.xz mydir #Create a tarball and compress it with xz
  tar -xvf mydir.tar.gz #Extract files into the mydir directory