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1 | .\" -*-nroff-*- |
2 | .\" |
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3 | .\" $Id: sw-env.5,v 1.3 1999/07/30 18:44:32 mdw Exp $ |
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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 | .\"----- Revision history --------------------------------------------------- |
29 | .\" |
30 | .\" $Log: sw-env.5,v $ |
f73dea54 |
31 | .\" Revision 1.3 1999/07/30 18:44:32 mdw |
32 | .\" Improve cross-references and tidy up formatting. |
33 | .\" |
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34 | .\" Revision 1.2 1999/07/16 12:45:37 mdw |
35 | .\" Internal formatting improvements. |
36 | .\" |
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37 | .\" Revision 1.1 1999/06/04 13:56:18 mdw |
38 | .\" New manual page. |
39 | .\" |
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40 | . |
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41 | .\" --- Useful macro definitions --- |
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42 | . |
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43 | .de VS \" Start a sort-of verbatim block |
44 | .sp 1 |
45 | .in +5n |
46 | .nf |
47 | .ft B |
48 | .. |
49 | .de VE \" Stop a sort-of verbatim block |
50 | .ft R |
51 | .fi |
52 | .in -5n |
53 | .sp 1 |
54 | .. |
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55 | .de hP \" Start an indented paragraph with a bold right-aligned label |
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56 | .IP |
57 | \fB\h'-\w'\\$1\ 'u'\\$1\ \fP\c |
58 | .. |
59 | .\" |
60 | .\" --- Style hacking --- |
61 | .\" |
62 | .ie \n(.g \{\ |
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63 | . fam P |
64 | . ds mw \fR[\f(BImdw\fR] |
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65 | .\} |
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66 | .el .ds mw \fR[\fBmdw\fR] |
67 | .ie t .ds o \(bu |
68 | .el .ds o o |
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69 | .ds sw \fBsw\fP |
70 | .ds se \fBsw\-env\fP |
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71 | . |
72 | .\"----- Main manual text --------------------------------------------------- |
73 | . |
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74 | .TH sw-env 5 "25 May 1999" sw-tools |
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75 | .PD 1 |
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76 | . |
77 | .\"-------------------------------------------------------------------------- |
78 | . |
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79 | .SH NAME |
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80 | . |
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81 | sw\-env \- environment variable assignment files for \*(sw. |
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82 | . |
83 | .\"-------------------------------------------------------------------------- |
84 | . |
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85 | .SH "DESCRIPTION" |
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86 | . |
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87 | A \*(se file is a sequence of statements. The following statements are |
88 | supported: |
89 | .sp 1 |
90 | .in +5n |
91 | .B : |
92 | .I value |
93 | .RB [ ; ] |
94 | .br |
95 | .B include |
96 | .I value |
97 | .RB [ ; ] |
98 | .br |
99 | .B arch |
100 | .I value |
101 | .B { |
102 | .IR statement ... |
103 | .B } |
104 | .RB [ ; ] |
105 | .br |
106 | .RB [ set ] |
107 | .I name |
108 | .RB [ = ] |
109 | .I value |
110 | .RB [ ; ] |
111 | .br |
112 | .B unset |
113 | .I name |
114 | .RB [ ; ] |
115 | .in -5n |
116 | .sp 1 |
117 | Whitespace serves to separate tokens but is otherwise ignored except |
118 | when it occurs quoted within a |
119 | .IR value . |
120 | The file may also contain comments, which begin with a |
121 | .RB ` # ' |
122 | character and extend to the end of the line. The start of a comment |
123 | must appear where a new statement is expected. Apart from its behaviour |
124 | of terminating comments, newlines behave the same way as other |
125 | whitespace characters. Keywords are not reserved words. |
126 | .PP |
127 | A |
128 | .I name |
129 | is a sequence of digits, letters and underscores which does not start |
130 | with a digit. |
131 | .PP |
132 | A |
133 | .I value |
134 | may contain any non-null character, although some characters are special |
135 | and must be quoted. The syntax of |
136 | .IR value s |
137 | is loosely based on the Bourne |
138 | shell, although there are differences and irregularities due to the |
139 | quick and dirty nature of the parser. The various quoting and |
140 | substitution operations are described below. |
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141 | . |
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142 | .SS "Statements" |
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143 | . |
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144 | The statements behave as follows: |
145 | .TP |
146 | .B : |
147 | The following |
148 | .I value |
149 | is read and discarded. This is not useless: reading a |
150 | .I value |
151 | may cause variables to be assigned as a result of |
152 | `\c |
153 | .BI ${ name = value }\c |
154 | \&' substitutions. |
155 | .TP |
156 | .B include |
157 | A |
158 | .I value |
159 | is read, and further assignments are read from the file so named, if it |
160 | exists. Conventionally, the last statement in the global \*(se file is |
161 | .VS |
162 | include ".sw-env"; |
163 | .VE |
164 | to read in package-specific settings. |
165 | .TP |
166 | .B arch |
167 | The following |
168 | .I value |
169 | is read. If it matches the name of the host's architecture, then the |
170 | brace-enclosed statements are executed; otherwise they're ignored. It's |
171 | possible, though not useful, to nest |
172 | .B arch |
173 | statements. |
174 | .TP |
175 | .B set |
176 | A |
177 | .I name |
178 | and |
179 | .I value |
180 | are read, optionally separated by an |
181 | .RB ` = ' |
182 | character. The variable named is assigned the value, replacing any |
183 | previously assigned value, if any. The |
184 | .RB ` set ' |
185 | keyword is optional. It's only useful so that you can assign values to |
186 | variables whose names are also statement keywords. |
187 | .TP |
188 | .B unset |
189 | A |
190 | .I name |
191 | is read. Any value assigned to the variable named is discarded, and the |
192 | variable is forgotten. |
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193 | . |
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194 | .SS "Value syntax" |
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195 | . |
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196 | The parser usually reads a |
197 | .I value |
198 | a character by character, until it finds a delimiter. Delimiter |
199 | characters are |
200 | .RB ` ( ', |
201 | .RB ` ) ', |
202 | .RB ` { ', |
203 | .RB ` } ', |
204 | and |
205 | .RB ` ; '; |
206 | whitespace also acts as a delimiter. Delimiter characters can only |
207 | appear in a value if quoted. |
208 | .PP |
209 | There are three types of quoting understood by the value reader. A |
210 | backslash |
211 | .RB (` \e ') |
212 | character causes the following character to be stripped of its special |
213 | meaning. Hence |
214 | .RB ` \e\e ' |
215 | inserts a literal backslash. Text between single quotes |
216 | .RB ` \' ... \' ' |
217 | is read |
218 | entirely as-is, including all whitespace, newlines, backslashes, |
219 | everything. To include a single quote in a piece of single-quoted text, |
220 | use the sequence |
221 | .RB ` \'\e\'\' ', |
222 | as in the shell. (This drops out of single-quoting, inserts an escaped |
223 | single quote, and resumes quoting.) Text between double quotes |
224 | .BR """" ... """" |
225 | is partially quoted: delimiters and whitespace are read as normal |
226 | characters, but substitutions using the |
227 | .RB ` $ ' |
228 | and |
229 | .RB ` \` ' |
230 | characters are still made, and the backslash retains its behaviour of |
231 | escaping the following character. |
232 | .PP |
233 | Two sorts of substitutions are available in values: |
234 | .I "variable substitution" |
235 | examines a variable and substitutes some text based on its value, and |
236 | .I "command substitution" |
237 | runs a command and substitutes its output. |
238 | .PP |
239 | The simplest variable substitution takes the form |
240 | .RB ` $\c |
241 | .IR name ': |
242 | this is replaced by the value of the variable called |
243 | .IR name , |
244 | or the empty string if there is no such variable defined. The name may |
245 | be enclosed in braces should it be necessary to clearly disambiguate the |
246 | end of the name. |
247 | .PP |
248 | More complex variable substitutions are permitted: |
249 | .TP |
250 | .BI ${ name \- text } |
251 | Expands to the value of the variable called |
252 | .I name |
253 | if it's defined, or |
254 | .I text |
255 | if not. |
256 | .TP |
257 | .BI ${ name + text } |
258 | Expands to |
259 | .I text |
260 | if there is a variable called |
261 | .I name |
262 | defined, or nothing. |
263 | .TP |
264 | .BI ${ name = text } |
265 | If there is no variable called |
266 | .I name |
267 | then create one with the value |
268 | .IR text ; |
269 | then expands to the variable's value. |
270 | .PP |
271 | In each of the above, prefixing the operator character |
272 | .RB ` \- ', |
273 | .RB ` + ' |
274 | or |
275 | .RB ` = ' |
276 | with a colon |
277 | .RB (` : ') |
278 | changes the variable existence test, such that it will believe that a |
279 | variable whose value is the empty string is not defined. Each |
280 | .I text |
281 | part in the above forms is syntactically a |
282 | .IR value , |
283 | and may itself contain quoting and substitutions. It may also contain |
284 | unescaped whitespace. |
285 | .PP |
286 | There are two forms for command substitution: the backtick form, where a |
287 | command is enclosed in backquotes |
288 | .RB ` \` ... \` '; |
289 | and the parenthesized form |
290 | .RB ` $( ... ) '. |
291 | The only difference between these two forms is syntactic: it's easy to |
292 | make the parenthesized version nest, although that's not actually very |
293 | useful. The text between the backquotes or parentheses is broken into |
294 | words and executed as a command. It is not passed through the shell: |
295 | the author suspects that this would be too confusing. The standard |
296 | output of the command, with trailing newlines (but not internal or |
297 | leading newlines) removed, is the result of the substitution. |
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298 | . |
299 | .\"-------------------------------------------------------------------------- |
300 | . |
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301 | .SH "AUTHOR" |
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302 | . |
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303 | The \*(sw program, and this manual, are \*(mw productions, in association |
304 | with the European Bioinformatics Institute. They were written by Mark |
305 | Wooding <mdw@nsict.org>. Go and ask him if you have problems. |
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306 | . |
307 | .\"----- That's all, folks -------------------------------------------------- |