Force Output Redirection

The >| operator is a standard output (stdout) redirection operator in Bash that forces the truncation and overwriting of an existing file, explicitly bypassing the noclobber shell option (set -C).

Syntax

[fd]>| filename

• fd: (Optional) The file descriptor to redirect. Defaults to 1 (standard output).
• filename: The target file to receive the redirected stream.

Execution Mechanics

The mechanical distinction of >| is strictly tied to the state of the shell’s noclobber option:

1. noclobber Disabled (Default State): When set +o noclobber is active, the standard > operator and the >| operator are functionally identical. Both will truncate an existing file to zero bytes before writing the new output stream.
2. noclobber Enabled: When set -o noclobber (or set -C) is active, the shell prevents the standard > operator from overwriting existing regular files, yielding a cannot overwrite existing file error. The >| operator overrides this internal shell restriction, forcing the truncation and write operation to proceed regardless of the noclobber state.

Technical Constraints

• POSIX Compliance: The >| operator is defined in the POSIX shell command language specification (IEEE Std 1003.1). It is a standard feature, not a Bash-specific extension.
• Filesystem Permissions: The operator only overrides the shell’s internal noclobber safeguard. It does not bypass operating system-level file permissions. If the target file lacks write permissions (-w), or if the file is marked immutable by the filesystem, >| will still fail with a Permission denied error.
• Non-Regular Files: The noclobber option only protects regular files. Redirecting to character special files (e.g., /dev/null, /dev/tty) or FIFOs is unaffected by noclobber, making >| mechanically equivalent to > when targeting these file types.

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