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75 lines
2.4 KiB
Plaintext
75 lines
2.4 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "UNSETENV" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" unsetenv
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.SH NAME
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unsetenv \- remove an environment variable
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.SH SYNOPSIS
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.LP
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\fB#include <stdlib.h>
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.br
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.sp
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int unsetenv(const char *\fP\fIname\fP\fB); \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIunsetenv\fP() function shall remove an environment variable
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from the environment of the calling process. The \fIname\fP
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argument points to a string, which is the name of the variable to
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be removed. The named argument shall not contain an \fB'='\fP
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character. If the named variable does not exist in the current environment,
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the environment shall be unchanged and the function is
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considered to have completed successfully.
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.LP
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If the application modifies \fIenviron\fP or the pointers to which
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it points, the behavior of \fIunsetenv\fP() is undefined.
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The \fIunsetenv\fP() function shall update the list of pointers to
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which \fIenviron\fP points.
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.LP
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The \fIunsetenv\fP() function need not be reentrant. A function that
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is not required to be reentrant is not required to be
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thread-safe.
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.SH RETURN VALUE
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.LP
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Upon successful completion, zero shall be returned. Otherwise, -1
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shall be returned, \fIerrno\fP set to indicate the error, and
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the environment shall be unchanged.
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.SH ERRORS
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.LP
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The \fIunsetenv\fP() function shall fail if:
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.TP 7
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.B EINVAL
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The \fIname\fP argument is a null pointer, points to an empty string,
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or points to a string containing an \fB'='\fP
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character.
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.sp
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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None.
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.SH RATIONALE
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.LP
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Refer to the RATIONALE section in \fIsetenv\fP() .
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIgetenv\fP() , \fIsetenv\fP() , the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, \fI<stdlib.h>\fP, \fI<sys/types.h>\fP, \fI<unistd.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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