Shell pipe operator

A vertical bar joining one command's output to the next command's input.

Also known as: Pipe operator

Everyday & digitalStandard profile

Meanings

Between two commands, the vertical bar connects the first one's output stream directly to the second one's input, so that data flows through a chain without touching a file.

Officially standardisedVerified fact
POSIX defines the vertical bar as the pipe operator: it connects the standard output of the command on its left to the standard input of the command on its right.
Contexts: Software
Common modern usageVerified fact
Introduced in Unix in 1973 and now the defining idiom of shell composition: many small programs chained rather than one large one.
Contexts: Software

Visual description

A single upright stroke of even weight, standing the full height of a line of text with no head or foot.

Symmetry: vertical
Orientation: upright

Commonly confused with: Vertical bar
The same character. The vertical bar is the typographic mark; the pipe operator is what a shell does with it.
Part of the same system as: Output redirection operator
Both are used in software contexts.

Compare: Vertical bar vs shell pipe operator →

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references.

Sources

Pipeline (Unix)
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for widely-agreed identity, origin and current use, not for contested detail or exact dates.
POSIX.1-2024, Shell Command Language
The Open Group / IEEE · retrieved 2026-08-01
Cited for the shell's operator grammar — which characters are operators and what they do — and for nothing outside it. It standardises a notation that already existed rather than inventing one, so records here describe documented practice that POSIX also pins down.

Last reviewed 2026-08-01

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Shell operators

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Meanings

Between two commands, the vertical bar connects the first one's output stream directly to the second one's input, so that data flows through a chain without touching a file.

Officially standardisedVerified fact

POSIX defines the vertical bar as the pipe operator: it connects the standard output of the command on its left to the standard input of the command on its right.

Contexts: Software

Common modern usageVerified fact

Introduced in Unix in 1973 and now the defining idiom of shell composition: many small programs chained rather than one large one.

Contexts: Software

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references.

Sources

Pipeline (Unix)
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for widely-agreed identity, origin and current use, not for contested detail or exact dates.
POSIX.1-2024, Shell Command Language
The Open Group / IEEE · retrieved 2026-08-01
Cited for the shell's operator grammar — which characters are operators and what they do — and for nothing outside it. It standardises a notation that already existed rather than inventing one, so records here describe documented practice that POSIX also pins down.

Last reviewed 2026-08-01

Meanings

Visual description

Related & commonly confused symbols

Meanings

Visual description

Related & commonly confused symbols