Bash / Command Line Pipes and Redirection

Part of Linux

# default fds
0 stdin
1 stdout
2 stderr

# run program1, stdout/stderr to terminal (default)
program1

# send stdout from program1 to stdin of program2 with anonymous pipe
program1 | program2

# run program1, stdout to out.log, stderr to terminal
program1 1> out.log
program1> out.log

# run program1, stdout/stderr to out.log, nothing to terminal
program1 1> out.log 2> out.log
program1> out.log 2> out.log
program1> out.log 2>&1

# run program1 with input.txt as input,
# stdout/stderr to terminal
program1 <input.txt
cat input.txt | program1

# run program1 with input.txt to stdin,
# stdout to output.txt, stderr to terminal
program1 <input.txt> output.txt
cat input.txt | program1> output.txt

# send stdout from program1 to stdin of program2 with named pipe
mkfifo mypipe
program1> mypipe
program2 <mypipe

# run program1, discard all output
program1> /dev/null 2>&1