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1 | .\" -*-nroff-*- |
2 | .\" |
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3 | .\" $Id$ |
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4 | .\" |
5 | .\" Manual page for `sw-env' files |
6 | .\" |
7 | .\" (c) 1999 EBI |
8 | .\" |
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9 | . |
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10 | .\"----- Licensing notice --------------------------------------------------- |
11 | .\" |
12 | .\" This file is part of sw-tools. |
13 | .\" |
14 | .\" sw-tools is free software; you can redistribute it and/or modify |
15 | .\" it under the terms of the GNU General Public License as published by |
16 | .\" the Free Software Foundation; either version 2 of the License, or |
17 | .\" (at your option) any later version. |
18 | .\" |
19 | .\" sw-tools is distributed in the hope that it will be useful, |
20 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | .\" GNU General Public License for more details. |
23 | .\" |
24 | .\" You should have received a copy of the GNU General Public License |
25 | .\" along with sw-tools; if not, write to the Free Software Foundation, |
26 | .\" Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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27 | . |
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28 | .\" --- Useful macro definitions --- |
29 | . |
30 | .de VS \" Start a sort-of verbatim block |
31 | .sp 1 |
32 | .in +5n |
33 | .nf |
34 | .ft B |
35 | .. |
36 | .de VE \" Stop a sort-of verbatim block |
37 | .ft R |
38 | .fi |
39 | .in -5n |
40 | .sp 1 |
41 | .. |
42 | .de hP \" Start an indented paragraph with a bold right-aligned label |
43 | .IP |
44 | \fB\h'-\w'\\$1\ 'u'\\$1\ \fP\c |
45 | .. |
46 | .\" |
47 | .\" --- Style hacking --- |
48 | .\" |
49 | .ie \n(.g \{\ |
50 | . fam P |
51 | . ds mw \fR[\f(BImdw\fR] |
52 | .\} |
53 | .el .ds mw \fR[\fBmdw\fR] |
54 | .ie t .ds o \(bu |
55 | .el .ds o o |
56 | .ds sw \fBsw\fP |
57 | .ds se \fBsw\-env\fP |
58 | . |
59 | .\"----- Main manual text --------------------------------------------------- |
60 | . |
61 | .TH sw-env 5 "25 May 1999" sw-tools |
62 | .PD 1 |
63 | . |
64 | .\"-------------------------------------------------------------------------- |
65 | . |
66 | .SH NAME |
67 | . |
68 | sw\-env \- environment variable assignment files for \*(sw. |
69 | . |
70 | .\"-------------------------------------------------------------------------- |
71 | . |
72 | .SH "DESCRIPTION" |
73 | . |
74 | A \*(se file is a sequence of statements. The following statements are |
75 | supported: |
76 | .sp 1 |
77 | .in +5n |
78 | .B : |
79 | .I value |
80 | .RB [ ; ] |
81 | .br |
82 | .B include |
83 | .I value |
84 | .RB [ ; ] |
85 | .br |
86 | .B arch |
87 | .I value |
88 | .B { |
89 | .IR statement ... |
90 | .B } |
91 | .RB [ ; ] |
92 | .br |
93 | .RB [ set ] |
94 | .I name |
95 | .RB [ = ] |
96 | .I value |
97 | .RB [ ; ] |
98 | .br |
99 | .B unset |
100 | .I name |
101 | .RB [ ; ] |
102 | .in -5n |
103 | .sp 1 |
104 | Whitespace serves to separate tokens but is otherwise ignored except |
105 | when it occurs quoted within a |
106 | .IR value . |
107 | The file may also contain comments, which begin with a |
108 | .RB ` # ' |
109 | character and extend to the end of the line. The start of a comment |
110 | must appear where a new statement is expected. Apart from its behaviour |
111 | of terminating comments, newlines behave the same way as other |
112 | whitespace characters. Keywords are not reserved words. |
113 | .PP |
114 | A |
115 | .I name |
116 | is a sequence of digits, letters and underscores which does not start |
117 | with a digit. |
118 | .PP |
119 | A |
120 | .I value |
121 | may contain any non-null character, although some characters are special |
122 | and must be quoted. The syntax of |
123 | .IR value s |
124 | is loosely based on the Bourne |
125 | shell, although there are differences and irregularities due to the |
126 | quick and dirty nature of the parser. The various quoting and |
127 | substitution operations are described below. |
128 | . |
129 | .SS "Statements" |
130 | . |
131 | The statements behave as follows: |
132 | .TP |
133 | .B : |
134 | The following |
135 | .I value |
136 | is read and discarded. This is not useless: reading a |
137 | .I value |
138 | may cause variables to be assigned as a result of |
139 | `\c |
140 | .BI ${ name = value }\c |
141 | \&' substitutions. |
142 | .TP |
143 | .B include |
144 | A |
145 | .I value |
146 | is read, and further assignments are read from the file so named, if it |
147 | exists. Conventionally, the last statement in the global \*(se file is |
148 | .VS |
149 | include ".sw-env"; |
150 | .VE |
151 | to read in package-specific settings. |
152 | .TP |
153 | .B arch |
154 | The following |
155 | .I value |
156 | is read. If it matches the name of the host's architecture, then the |
157 | brace-enclosed statements are executed; otherwise they're ignored. It's |
158 | possible, though not useful, to nest |
159 | .B arch |
160 | statements. |
161 | .TP |
162 | .B set |
163 | A |
164 | .I name |
165 | and |
166 | .I value |
167 | are read, optionally separated by an |
168 | .RB ` = ' |
169 | character. The variable named is assigned the value, replacing any |
170 | previously assigned value, if any. The |
171 | .RB ` set ' |
172 | keyword is optional. It's only useful so that you can assign values to |
173 | variables whose names are also statement keywords. |
174 | .TP |
175 | .B unset |
176 | A |
177 | .I name |
178 | is read. Any value assigned to the variable named is discarded, and the |
179 | variable is forgotten. |
180 | . |
181 | .SS "Value syntax" |
182 | . |
183 | The parser usually reads a |
184 | .I value |
185 | a character by character, until it finds a delimiter. Delimiter |
186 | characters are |
187 | .RB ` ( ', |
188 | .RB ` ) ', |
189 | .RB ` { ', |
190 | .RB ` } ', |
191 | and |
192 | .RB ` ; '; |
193 | whitespace also acts as a delimiter. Delimiter characters can only |
194 | appear in a value if quoted. |
195 | .PP |
196 | There are three types of quoting understood by the value reader. A |
197 | backslash |
198 | .RB (` \e ') |
199 | character causes the following character to be stripped of its special |
200 | meaning. Hence |
201 | .RB ` \e\e ' |
202 | inserts a literal backslash. Text between single quotes |
203 | .RB ` \' ... \' ' |
204 | is read |
205 | entirely as-is, including all whitespace, newlines, backslashes, |
206 | everything. To include a single quote in a piece of single-quoted text, |
207 | use the sequence |
208 | .RB ` \'\e\'\' ', |
209 | as in the shell. (This drops out of single-quoting, inserts an escaped |
210 | single quote, and resumes quoting.) Text between double quotes |
211 | .BR """" ... """" |
212 | is partially quoted: delimiters and whitespace are read as normal |
213 | characters, but substitutions using the |
214 | .RB ` $ ' |
215 | and |
216 | .RB ` \` ' |
217 | characters are still made, and the backslash retains its behaviour of |
218 | escaping the following character. |
219 | .PP |
220 | Two sorts of substitutions are available in values: |
221 | .I "variable substitution" |
222 | examines a variable and substitutes some text based on its value, and |
223 | .I "command substitution" |
224 | runs a command and substitutes its output. |
225 | .PP |
226 | The simplest variable substitution takes the form |
227 | .RB ` $\c |
228 | .IR name ': |
229 | this is replaced by the value of the variable called |
230 | .IR name , |
231 | or the empty string if there is no such variable defined. The name may |
232 | be enclosed in braces should it be necessary to clearly disambiguate the |
233 | end of the name. |
234 | .PP |
235 | More complex variable substitutions are permitted: |
236 | .TP |
237 | .BI ${ name \- text } |
238 | Expands to the value of the variable called |
239 | .I name |
240 | if it's defined, or |
241 | .I text |
242 | if not. |
243 | .TP |
244 | .BI ${ name + text } |
245 | Expands to |
246 | .I text |
247 | if there is a variable called |
248 | .I name |
249 | defined, or nothing. |
250 | .TP |
251 | .BI ${ name = text } |
252 | If there is no variable called |
253 | .I name |
254 | then create one with the value |
255 | .IR text ; |
256 | then expands to the variable's value. |
257 | .PP |
258 | In each of the above, prefixing the operator character |
259 | .RB ` \- ', |
260 | .RB ` + ' |
261 | or |
262 | .RB ` = ' |
263 | with a colon |
264 | .RB (` : ') |
265 | changes the variable existence test, such that it will believe that a |
266 | variable whose value is the empty string is not defined. Each |
267 | .I text |
268 | part in the above forms is syntactically a |
269 | .IR value , |
270 | and may itself contain quoting and substitutions. It may also contain |
271 | unescaped whitespace. |
272 | .PP |
273 | There are two forms for command substitution: the backtick form, where a |
274 | command is enclosed in backquotes |
275 | .RB ` \` ... \` '; |
276 | and the parenthesized form |
277 | .RB ` $( ... ) '. |
278 | The only difference between these two forms is syntactic: it's easy to |
279 | make the parenthesized version nest, although that's not actually very |
280 | useful. The text between the backquotes or parentheses is broken into |
281 | words and executed as a command. It is not passed through the shell: |
282 | the author suspects that this would be too confusing. The standard |
283 | output of the command, with trailing newlines (but not internal or |
284 | leading newlines) removed, is the result of the substitution. |
285 | . |
286 | .\"-------------------------------------------------------------------------- |
287 | . |
288 | .SH "AUTHOR" |
289 | . |
290 | The \*(sw program, and this manual, are \*(mw productions, in association |
291 | with the European Bioinformatics Institute. They were written by Mark |
292 | Wooding <mdw@nsict.org>. Go and ask him if you have problems. |
293 | . |
294 | .\"----- That's all, folks -------------------------------------------------- |