Decoded: unlink (coreutils)

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Note: This page explores the design of command-line utilities. It is not a user guide.
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Summary

unlink - remove files via the unlink syscall

[Source] [Code Walkthrough]

Lines of code: 96
Principal syscall: unlink()
Support syscalls: None
Options: 0 (help and version built in to usage())

Existed as a syscall since Version 1 UNIX (1971). Wrapper utility unique to coreutils
Added to Coreutils in April 2002 [First version]
Number of revisions: 51 [Code Evolution]

Helpers:

• None

External non-standard helpers:

• die() - Exit with mandatory non-zero error and message to stderr
• error() - Outputs error message to standard error with possible process termination

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Setup

unlink initializes no parsing options, globals, or additional variables in main() not already mentioned.

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Parsing

Parsing for unlink involves checking that a single argument references a file.

Parsing failures

These failure case is explicitly checked:

• No file provided
• More than one file provided

Failure results in a short error message followed by the usage instructions.

Execution

Successful execution happens with one line of code: unlink (argv[optind]).

Failure case:

• unlink() returned an error for any reason. The reason for failure is not checked.

All failures at this stage output an error message to STDERR and return without displaying usage help

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