Special symbols

Arrows

./program > output.out (> for stdout)
./program 2> err (2> for stderr)
./program >> output.out (>> attach to the end)
./program < input.in
./program -k blah 2 < input.in > output.out

File descriptor 1 is the standard output (stdout). File descriptor 2 is the standard error (stderr).

Quotes

• ' single quote: string literals
• " double quote: suppresses wildcard but not variables

Flags

Use single dash - for options (should be right next to the command)

-- followed by subcommands

The -- tells not to try to parse what comes after it as command line options.