Computer Dictionary Online

Medical Dictionary   Law Dictionary   Legal Dictionary   Website Design

0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z 


input/output redirection

<operating system> In Unix, to send ouput from a process to different file or device or to another process via a pipe, or to have a process read its input from a different file, device or pipe. Some other operating systems have similar facilities.

To redirect input to come from a file instead of the keyboard, use "<":

		myprog < myfile


Similarly to redirect output to a file instead of the screen:

		ls > filelist


A pipe redirects the output of one process directly into the input of another

		who | wc -l


A common misuse by beginners is

		cat myfile | myprog


Which is more or less equivalent to "myprog < myfile" except that it introduces an extra unnecessary cat process and buffer space for the pipe. Even the "<" is unnecessary with many standard Unix commands since they accept input file names as command line arguments anyway.

Unix's concept of standard input/output and I/O redirection make it easy to combine simple processes in powerful ways and to use the same commands for different purposes.

(1998-04-24)


Contact the Computer Dictionary Online  ::  Link to the Computer Dictionary Online  ::  Disclaimer for Computer Dictionary Online

Computer Dictionary Online
Copyright © 2017