IO in Bash

Each open file gets assigned a file descriptor. [2] The file descriptors for stdin, stdout, and stderr are 0, 1, and 2, respectively.

Basics

Command	do
[cmd] > [filename]	Redirects stdout to file creating or overwriting	echo "hi" > test.txt
[cmd] >> [filename]	Appends stdout to file if it exists, or creates	echo "Thank you" >> test.txt
1>[filename]	redirect stdout to file	echo "Dream better" 1>$LOGFILE
2>[filename]	redirect stdeer	bad_command1 2>$ERRORFILE
&>[filename] ORR >&[filename]	redirect both stdout and stderr
0< FILENAME	accept input from a file

Pipes

General purpose comman chaining

cat *.txt | sort | uniq > test.txt

Advanced Stupid Stuff

Cmd	do	Ex
: > [filename]	make file empty	: > test.txt
2>&1	Redirects stderr to stdout.