UNSETENV(3P)

💖 UNSETENV 💖 — a POSIX Programmer's Manual moment

okay bestie so this page is from the POSIX Programmer's Manual, and like… a lil heads up before we dive in: the Linux implementation of this interface may differ from what POSIX says (so pls consult the corresponding Linux manual page for the actual Linux behavior), or the interface might not even be implemented on Linux at all. iykyk 🫶

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🎀 PROLOG 🎀

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

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✨ NAME ✨

unsetenv — remove an environment variable 💅

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🌸 SYNOPSIS 🌸

#include <stdlib.h>

int unsetenv(const char *name);

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🦋 DESCRIPTION 🦋

So unsetenv() shall remove an environment variable from the environment of the calling process. simple as that, no cap.

The name argument points to a string, which is the name of the variable to be removed. and bestie, listen — the name argument shall not contain an '=' character. not even one. we do not do that here. 💀

If the named variable does not exist in the current environment, the environment shall be unchanged and the function is considered to have completed successfully. like, nothing happens, and that's a win actually. 🌈

The unsetenv() function shall update the list of pointers to which environ points.

⚠️ also important: the unsetenv() function need not be thread-safe. so like, be careful out there in multithreaded land, bestie. 😭

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⭐ RETURN VALUE ⭐

Upon successful completion, zero shall be returned. 🎉

Otherwise, -1 shall be returned, errno set to indicate the error, and the environment shall be unchanged. (so it fails cleanly, which is honestly iconic of it.) 💜

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🔥 ERRORS 🔥

The unsetenv() function shall fail if:

• EINVAL — The name argument points to an empty string, or points to a string containing an '=' character. 🚫

The following sections are informative.

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🍓 EXAMPLES 🍓

None.

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🧚 APPLICATION USAGE 🧚

None.

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👑 RATIONALE 👑

Refer to the RATIONALE section in setenv().

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💀 FUTURE DIRECTIONS 💀

None.

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🌈 SEE ALSO 🌈

getenv(), setenv()

The Base Definitions volume of POSIX.1‐2017, <stdlib.h>, <sys_types.h>

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💖 COPYRIGHT 💖

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page, bestie 🫶 this little baddie came to you courtesy of IEEE/The Open Group, dated 2017, and it's the UNSETENV(3P) page — go forth and unset those variables responsibly, mwah 💅✨