Pipelines: Difference between revisions
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Every program receives "standard in", and sends its output to "standard out". By default, stdin is taken from the keyboard, and stdout will display something to the screen. These mappings can be adjusted however using ''redirection'' using the special pipeline characters '>', '<', and '|'. | Every program receives "standard in", and sends its output to "standard out". By default, stdin is taken from the keyboard, and stdout will display something to the screen. These mappings can be adjusted however using ''redirection'' using the special pipeline characters '>', '<', and '|'. | ||
== Redirecting ''stdout'' with > == | |||
date | |||
Displays the date to the screen (no stdin used by date). | |||
date > time.txt | |||
Redirects the output of date and "saves as" time.txt. | |||
cat time.txt | |||
Display time.txt (to the screen by default) | |||
== Redirecting ''stdin'' with < == | |||
== Piping (stdin=>stdout) with | == | |||
Revision as of 10:55, 20 February 2013
Philosophy of the commandline: Small tools that do one thing very well, loosely connected together to make custom "pipelines" or workflows to do specific (or surprising) things.
stdin and stdout
Every program receives "standard in", and sends its output to "standard out". By default, stdin is taken from the keyboard, and stdout will display something to the screen. These mappings can be adjusted however using redirection using the special pipeline characters '>', '<', and '|'.
Redirecting stdout with >
date
Displays the date to the screen (no stdin used by date).
date > time.txt
Redirects the output of date and "saves as" time.txt.
cat time.txt
Display time.txt (to the screen by default)