1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
.\"
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\"
.\" The GNU General Public License's references to "object code"
.\" and "executables" are to be interpreted as the output of any
.\" document formatting or typesetting system, including
.\" intermediate and printed output.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
.\" License along with this manual; if not, write to the Free
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
.\" USA.
.\"
.TH WORDEXP 3 2003-11-11 "" "Linux Programmer's Manual"
.SH NAME
wordexp, wordfree \- perform word expansion like a posix-shell
.SH SYNOPSIS
.sp
.B "#include <wordexp.h>"
.sp
.BI "int wordexp(const char *" s ", wordexp_t *" p ", int " flags );
.sp
.BI "void wordfree(wordexp_t *" p );
.sp
.SH DESCRIPTION
The function
.B wordexp()
performs a shell-like expansion of the string
.I s
and returns the result in the structure pointed to by
.IR p .
The data type
.B wordexp_t
is a structure that at least has the fields
.IR we_wordc ,
.IR we_wordv ,
and
.IR we_offs .
The field
.I we_wordc
is a
.B size_t
that gives the number of words in the expansion of
.IR s .
The field
.I we_wordv
is a
.B char **
that points to the array of words found.
The field
.I we_offs
of type
.B size_t
is sometimes (depending on
.IR flags ,
see below) used to indicate the number of initial elements in the
.I we_wordv
array that should be filled with NULLs.
.LP
The function
.B wordfree()
frees the allocated memory again. More precisely, it does not free
its argument, but it frees the array
.I we_wordv
and the strings that points to.
.SH EXAMPLE
First a small example. The output is approximately that of "ls [a-c]*.c".
.LP
.nf
#include <stdio.h>
#include <wordexp.h>
int main(int argc, char **argv) {
wordexp_t p;
char **w;
int i;
wordexp("[a-c]*.c", &p, 0);
w = p.we_wordv;
for (i=0; i<p.we_wordc; i++)
printf("%s\en", w[i]);
wordfree(&p);
return 0;
}
.fi
.SH DETAILS
.SS "The string argument"
Since the expansion is the same as the expansion by the shell (see
.BR sh (1))
of the parameters to a command, the string
.I s
must not contain characters that would be illegal in shell command
parameters. In particular, there must not be any non-escaped
newline or |, &, ;, <, >, (, ), {, } characters
outside a command substitution or parameter substitution context.
.LP
If the argument
.I s
contains a word that starts with an unquoted comment character #,
then it is unspecified whether that word and all following words
are ignored, or the # is treated as a non-comment character.
.SS "The expansion"
The expansion done consists of the following stages:
tilde expansion (replacing ~user by user's home directory),
variable substitution (replacing $FOO by the value of the environment
variable FOO), command substitution (replacing $(command) or `command`
by the output of command), arithmetic expansion, field splitting,
wildcard expansion, quote removal.
.LP
The result of expansion of special parameters
($@, $*, $#, $?, $-, $$, $!, $0) is unspecified.
.LP
Field splitting is done using the environment variable $IFS.
If it is not set, the field separators are space, tab and newline.
.SS "The output array"
The array
.I we_wordv
contains the words found, followed by a NULL.
.SS "The flags argument"
The
.I flag
argument is a bitwise inclusive OR of the following values:
.TP
.B WRDE_APPEND
Append the words found to the array resulting from a previous call.
.TP
.B WRDE_DOOFFS
Insert
.I we_offs
initial NULLs in the array
.IR we_wordv .
(These are not counted in the returned
.IR we_wordc .)
.TP
.B WRDE_NOCMD
Don't do command substitution.
.TP
.B WRDE_REUSE
The parameter
.I p
resulted from a previous call to
.BR wordexp() ,
and
.BR wordfree()
was not called. Reuse the allocated storage.
.TP
.B WRDE_SHOWERR
Normally during command substitution
.I stderr
is redirected to
.IR /dev/null .
This flag specifies that
.I stderr
is not to be redirected.
.TP
.B WRDE_UNDEF
Consider it an error if an undefined shell variable is expanded.
.SH "RETURN VALUE"
In case of success 0 is returned. In case of error
one of the following five values is returned.
.TP
.B WRDE_BADCHAR
Illegal occurrence of newline or one of |, &, ;, <, >, (, ), {, }.
.TP
.B WRDE_BADVAL
An undefined shell variable was referenced, and the WRDE_UNDEF flag
told us to consider this an error.
.TP
.B WRDE_CMDSUB
Command substitution occurred, and the WRDE_NOCMD flag
told us to consider this an error.
.TP
.B WRDE_NOSPACE
Out of memory.
.TP
.B WRDE_SYNTAX
Shell syntax error, such as unbalanced parentheses or
unmatched quotes.
.SH "CONFORMING TO"
XPG4, POSIX 1003.1-2003
.SH "SEE ALSO"
.BR fnmatch (3),
.BR glob (3)
|
