Standard Streams and File Manipulation

There are three standard streams in Linux.

1. stdin (Standard Input)

2. stdout (Standard Output)

3. stderr (Standard Error)

Some Linux commands

1) less: Opens output in separate windows. Example "less /var/log/syslog

2) pipe (|): Takes standard output of one command and feeds in to the next command as standard input. Example " ls -la /etc | less "

here stdin denotes 0. stdout denotes 1. stderr denotes 2

streams mean transfer data. Data is simple text in Linux.