2018-09-23



Just some thoughts  on  the  `overwrite'  command,  presented  in
Chapter 5.5 (page 152) of ``The UNIX Programming Environment''.

`sort -m -o file' is not really a replacement for it.

     `-o output-file'
     `--output=output-file'

     Write output to output-file instead of standard output.
     Normally,  sort  reads all input before opening output-
     file, so you can sort a file in place by using commands
     like  sort -o F F and cat F | sort -o F. However, it is
     often safer to output to an otherwise-unused  file,  as
     data  may  be  lost  if  the system crashes or sort en-
     counters an I/O or other serious error while a file  is
     being sorted in place. Also, sort with --merge (-m) can
     open the output file before reading  all  input,  so  a
     command  like  cat  F | sort -m -o F - G is not safe as
     sort might start writing F before cat is  done  reading
     it.  [0]


[0]  https://www.gnu.org/software/coreutils/manual/html_node/sort-
invocation.html#sort-invocation


http://marmaro.de/lue/        markus schnalke <meillo@marmaro.de>