LOGNAME(1P)

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.

NAME
logname — return the user's login name

SYNOPSIS

logname

DESCRIPTION
The logname utility shall write the user's login name to standard output. The login name shall be the string that would be returned by the getlogin() function defined in the System Interfaces volume of POSIX.1-2017. Under the conditions where the getlogin() function would fail, the logname utility shall write a diagnostic message to standard error and exit with a non-zero exit status.

OPTIONS
None.

OPERANDS
None.

STDIN
Not used.

INPUT FILES
None.

ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of logname:

LANG
    Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.1-2017, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.)

LC_ALL
    If set to a non-empty string value, override the values of all the other internationalization variables.

LC_CTYPE
    Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments).

LC_MESSAGES
    Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.

NLSPATH
    Determine the location of message catalogs for the processing of LC_MESSAGES.

ASYNCHRONOUS EVENTS
Default.

STDOUT
The logname utility output shall be a single line consisting of the user's login name:

    "%s\n", <login name>

STDERR
The standard error shall be used only for diagnostic messages.

OUTPUT FILES
None.

EXTENDED DESCRIPTION
None.

EXIT STATUS
The following exit values shall be returned:

0   Successful completion.

>0  An error occurred.

CONSEQUENCES OF ERRORS
Default.

The following sections are informative.

APPLICATION USAGE
The logname utility explicitly ignores the LOGNAME environment variable because environment changes could produce erroneous results.

EXAMPLES
None.

RATIONALE
The passwd file is not listed as required because the implementation may have other means of mapping login names.

FUTURE DIRECTIONS
None.

SEE ALSO
id, who

The Base Definitions volume of POSIX.1-2017, Chapter 8, Environment Variables

The System Interfaces volume of POSIX.1-2017, getlogin()

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 .