UNIX: Sorting & Pipe System

Flashcards covering key concepts from the UNIX Sorting & Pipe System lecture, including commands (wc, sort, uniq), input/output streams (stdin, stdout, stderr), and redirection/piping operators.

wc (word count)

A Unix tool that reports the number of lines, words, and characters in a file, typically used with text files.

sort

A Unix command that sorts the lines of a file into alphabetical (or other specified) order.

uniq

A Unix command that removes duplicate copies of adjacent lines from a file.

Input (Unix)

Everything a Unix program reads, usually from the keyboard (what you type).

Output (Unix)

Everything a Unix program writes, usually to the screen (what you see).

stdin (standard input)

The input stream from the keyboard, where programs typically expect user input.

stdout (standard output)

The output stream to the screen, where the results of a running program are displayed.

stderr (standard error)

The output stream for error messages, which also appear on the screen but can be separated from normal output.

(output redirection)

A redirection operator that sends all output normally going to stdout into a specified file, completely overwriting its contents or creating a new file.

< (input redirection)

A redirection operator that makes all input for a program come from a specified file instead of the keyboard.

(output append redirection)

A redirection operator that appends all output of a program to a specified file. It will create the file if it doesn't exist but will not overwrite existing information.

2> (stderr redirection)

A redirection operator specifically used to send error messages (stderr) to a specified file.

0 (stream identifier)

Represents stdin (standard input) in Unix stream notation.

1 (stream identifier)

Represents stdout (standard output) in Unix stream notation.

2 (stream identifier)

Represents stderr (standard error) in Unix stream notation.

| (pipe operator)

An operator in Unix that feeds the stdout of one program as the stdin to another program, chaining commands together.