shell - Dont understand (Pipes) usage unix -

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i studying 'operational systems' exams @ uni , having hard time understanding pipes usage (|). here example found on internet:

ps -ax | grep finder
use ps command list of processes running on system, , pass list grep search lines containing "finder". (usually, it'll find two: finder, , processes executing grep finder.)

what if first write ps -ax , @ next line grep finder ? wont have same result? why have pipe them together?

ps: bigginer @ unix shell commands , how works.

it's redirecting input , output.

if type ps -ax > processes, create file processes list of processes. redirecting output. data shown screen instead written file.

if type grep finder < processes, search file processes word finder. redirecting input.

pipe both. redirects output of command on left side , redirects input of command on right side.

$ ps -ax | grep finder

is like

$ ps -ax > temp $ grep finder < temp

except on 1 line no temp file delete.


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