coreutils: sum invocation

1 
1 6.2 ‘sum’: Print checksum and block counts
1 ==========================================
1 
1 ‘sum’ computes a 16-bit checksum for each given FILE, or standard input
1 if none are given or for a FILE of ‘-’.  Synopsis:
1 
1      sum [OPTION]... [FILE]...
1 
1    ‘sum’ prints the checksum for each FILE followed by the number of
1 blocks in the file (rounded up).  If more than one FILE is given, file
1 names are also printed (by default).  (With the ‘--sysv’ option,
1 corresponding file names are printed when there is at least one file
1 argument.)
1 
1    By default, GNU ‘sum’ computes checksums using an algorithm
1 compatible with BSD ‘sum’ and prints file sizes in units of 1024-byte
1 blocks.
1 
11    The program accepts the following options.  Also see ⇒Common
 options.
1 
1 ‘-r’
1      Use the default (BSD compatible) algorithm.  This option is
1      included for compatibility with the System V ‘sum’.  Unless ‘-s’
1      was also given, it has no effect.
1 
1 ‘-s’
1 ‘--sysv’
1      Compute checksums using an algorithm compatible with System V
1      ‘sum’’s default, and print file sizes in units of 512-byte blocks.
1 
1    ‘sum’ is provided for compatibility; the ‘cksum’ program (see next
1 section) is preferable in new applications.
1 
1    An exit status of zero indicates success, and a nonzero value
1 indicates failure.
1