Use of Linux bzip2 command

bzip2 [OPTIONS] [FILES...]

-c, --stdout
  Compress or decompress data to standard output -d, --decompress
  Force decompression. bzip2, bunzip2 and bzcat are actually the same program, and the operation they perform is determined by the program name. Specifying this option will override this mechanism and force bzip2 to decompress -z, --compress
	-d option supplement: force compression operation regardless of which program is executed -t, --test
  Checks the integrity of the specified file without decompressing it. In fact, the data will be experimentally decompressed without outputting the result -f, -force
  Force overwriting of output file. Normally bzip2 will not overwrite existing files. This option also forces bzip2 to break hard links in files, which bzip2 does not do by default.
-k, --keep
  Keep input files when compressing or decompressing (do not delete them)
-s, --small
  Reduce memory usage when compressing, decompressing, and checking. A modified algorithm is used for compression and testing, requiring only 2.5 bytes per data block. This means that any file can be decompressed in 2300K of memory, although at only half the normal speed. When compressing, -s will select a block length of 200K, and the memory usage will also be limited to around 200K, at the expense of a lower compression ratio. In summary, if the machine has low memory (8MB or less), use the -s option for all operations. -q, --quiet
  Suppress unimportant warning messages. Information about I/O errors and other serious events will not be suppressed -v, --verbose
  Verbose mode - displays the compression ratio of each processed file. More -v options on the command line will increase the verbosity level, causing bzip2 to display a lot of information mainly for diagnostic purposes. -L, --license, -V, --version
	Display software version, license terms and distribution conditions -1 (or --fast) to -9 (or --best)
  When compressing, set the block length to 100 k, 200 k, ... 900 k. Has no effect on decompression --
  Treat all subsequent command-line arguments as file names, even if they begin with a minus sign -. This option can be used to process file names starting with a minus sign -, for example: bzip2 -- -myfilename
--repetitive-fast, --repetitive-best
  These options are redundant in versions 0.9.5 and above. In earlier versions, these two options provided some coarse-grained control over the behavior of the sorting algorithm, which was useful in some situations. Versions 0.9.5 and above use an improved algorithm regardless of these options.

bzip2 /etc/passwd

bzip2 -k /etc/passwd
# or bzip2 -c /etc/passwd > /etc/passwd.bz2

bzip2 -v /etc/passwd
/etc/passwd: 2.256:1, 3.546 bits/byte, 55.67% saved, 1552 in, 688 out.

bzip2 -d /etc/passwd.bz2

bzip2 -dk /etc/passwd.bz2
# or bzip2 -dc /etc/passwd.bz2 > /etc/passwd

bzip2 -tv /etc/passwd.bz2
/etc/passwd.bz2: ok