all Python 3fileinputfunction

fileinput.isstdin()

reading state

Returns True if the last line was read from standard input rather than from a file.

Syntax

fileinput.isstdin() -> bool

Standard input is used when the file list is empty or contains '-'; filename() then returns '<stdin>'. inplace=True does not apply to stdin — the output goes to the screen, not to a file — and isstdin() helps notice that. A second pass over stdin yields no lines: the stream is not rewound.

Examples

import fileinput, io, sys
open('a.txt', 'w', encoding='utf-8').write('a1\n')
sys.stdin = io.StringIO('typed\n')
with fileinput.input(['a.txt', '-'], encoding='utf-8') as f:
    for line in f:
        print(fileinput.filename(), fileinput.isstdin())  # → a.txt False / <stdin> True

See also

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