mirror of https://github.com/mkerrisk/man-pages
140 lines
3.1 KiB
Groff
140 lines
3.1 KiB
Groff
.\" Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
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.\" Distributed under GPL
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.\" based on the description in glibc source and infopages
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.\"
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.\" Corrections and additions, aeb
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.TH ENVZ_ADD 3
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.SH NAME
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envz_add, envz_entry, envz_get, envz_merge,
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envz_remove, envz_strip \- environment string support
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.SH SYNOPSIS
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.nf
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.sp
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.B "#include <envz.h>"
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.sp
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.BI "error_t"
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.BI "envz_add(char **" envz ", size_t *" envz_len ,
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.ti 16n
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.BI "const char *" name ", const char *" value );
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.sp
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.BI "char *"
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.BI "envz_entry(const char *" envz ", size_t *" envz_len ", const char *" name );
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.sp
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.BI "char *"
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.BI "envz_get(const char *" envz ", size_t *" envz_len ", const char *" name );
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.sp
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.BI "error_t"
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.BI "envz_merge(char **" envz ", size_t *" envz_len ,
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.ti 16n
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.BI "const char *" envz2 ", size_t " envz2_len ", int " override );
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.sp
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.BI "void"
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.BI "envz_remove(char **" envz ", size_t *" envz_len ", const char *" name );
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.sp
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.BI "void"
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.BI "envz_strip(char **" envz ", size_t *" envz_len );
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.SH DESCRIPTION
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These functions are glibc-specific.
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.LP
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An argz vector is a pointer to a character buffer together with a length,
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see
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.BR argz_add (3).
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An envz vector is a special argz vector, namely one where the strings
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have the form "name=value". Everything after the first '=' is considered
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to be the value. If there is no '=', the value is taken to be NULL.
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(While the value in case of a trailing '=' is the empty string "".)
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.LP
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These functions are for handling envz vectors.
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.LP
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.BR envz_add ()
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adds the string
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.RI \&" name = value \&"
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(in case
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.I value
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is non-NULL) or
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.RI \&" name \&"
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(in case
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.I value
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is NULL) to the envz vector
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.RI (* envz ,* envz_len )
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and updates
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.RI * envz
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and
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.RI * envz_len .
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If an entry with the same
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.I name
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existed, it is removed.
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.LP
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.BR envz_entry ()
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looks for
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.I name
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in the envz vector
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.RI ( envz , envz_len )
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and returns the entry if found, or NULL if not.
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.LP
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.BR envz_get ()
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looks for
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.I name
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in the envz vector
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.RI ( envz , envz_len )
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and returns the value if found, or NULL if not.
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(Note that the value can also be NULL, namely when there is
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an entry for
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.I name
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without '=' sign.)
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.LP
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.BR envz_merge ()
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adds each entry in
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.I envz2
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to
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.RI * envz ,
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as if with
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.BR envz_add ().
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If
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.I override
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is true, then values in
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.I envz2
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will supersede those with the same name in
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.RI * envz ,
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otherwise not.
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.LP
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.BR envz_remove ()
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removes the entry for
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.I name
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from
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.RI (* envz ,* envz_len )
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if there was one.
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.LP
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.BR envz_strip ()
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removes all entries with value NULL.
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.SH "RETURN VALUE"
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All envz functions that do memory allocation have a return type of
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\fIerror_t\fP, and return 0 for success, and \fBENOMEM\fP
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if an allocation error occurs.
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.SH EXAMPLE
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.sp
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.nf
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#include <stdio.h>
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#include <envz.h>
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int
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main(int argc, char *argv[], char *envp[])
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{
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int i, e_len = 0;
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char *str;
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for (i=0; envp[i] != NULL; i++)
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e_len += strlen(envp[i]) + 1;
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str = envz_entry(*envp, e_len, "HOME");
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printf("%s\en", str);
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str = envz_get(*envp, e_len, "HOME");
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printf("%s\en", str);
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return 0;
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}
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.fi
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.SH "CONFORMING TO"
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These functions are a GNU extension. Handle with care.
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.SH "SEE ALSO"
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.BR argz (3)
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