{"id":23836,"date":"2022-08-19T15:32:12","date_gmt":"2022-08-19T10:02:12","guid":{"rendered":"http:\/\/www.pythonpool.com\/?p=23836"},"modified":"2026-07-13T12:40:47","modified_gmt":"2026-07-13T07:10:47","slug":"python-read-input-from-stdin","status":"publish","type":"post","link":"https:\/\/www.pythonpool.com\/python-read-input-from-stdin\/","title":{"rendered":"Read stdin in Python: input(), sys.stdin, Pipes, and EOF"},"content":{"rendered":"

Quick answer:<\/strong> Use input()<\/code> for one interactive line and sys.stdin<\/code> when a program must consume piped or redirected text. Decide whether to strip newlines, handle EOF, and process the stream lazily before choosing how much input to read.<\/p>\n

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input() is interactive, sys.stdin is a stream, and EOF, output routing, and text-versus-bytes boundaries are part of the CLI contract.<\/figcaption><\/figure>\n

stdin<\/code> is the standard input stream for a Python process. It is where text arrives when a user types into a terminal, pipes data into a command, or redirects a file into a script. Python gives you several ways to read it, depending on whether you need one prompt, one line, or a stream of many lines.<\/p>\n

Use input()<\/code> for interactive prompts. Use sys.stdin<\/code> when input may come from a pipe or a redirected file. Use fileinput<\/code> when a script should read either named files or standard input with the same loop.<\/p>\n

The right choice depends on how the program is called. A teaching script may ask one question and stop. A command-line utility may receive hundreds of lines from another command. A test may replace the stream with a small in-memory object. Treat those cases separately instead of forcing every script through one pattern.<\/p>\n

The official input documentation<\/a> covers interactive reads, the sys.stdin documentation<\/a> describes the standard stream, the fileinput documentation<\/a> covers file-or-stdin loops, and the unittest.mock documentation<\/a> helps with tests.<\/p>\n

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