1 This file documents things you should know to write a new debhelper program.
2 Any program with a name that begins with dh_ should conform to these
3 guidelines (with the historical exception of dh_make).
8 There are lots of debhelper commands. To make the learning curve shallower,
9 I want them all to behave in a standard manner:
11 All debhelper programs have names beginning with "dh_". This is so we don't
12 pollute the name space too much.
14 Debhelper programs should never output anything to standard output except
15 error messages, important warnings, and the actual commands they run that
16 modify files under debian/ (this last only if they are passed -v, and if you
17 output the commands, you should indent them with 1 tab). This is so we don't
18 have a lot of noise output when all the debhelper commands in a debian/rules
19 are run, so the important stuff is clearly visible.
21 Debhelper programs should accept all options listed in the "SHARED
22 DEBHELPER OPTIONS" section of debhelper(7), including any long forms of
23 these options, like --verbose . If necessary, the options may be ignored.
25 If debhelper commands need config files, they should use
26 debian/package.filename as the name of the config file (replace filename
27 with whatever your command wants), and debian/filename should also be
28 checked for config information for the first binary package in
29 debian/control. Also, debhelper commands should accept the same sort of
30 information that appears in the config files, on their command lines, if
31 possible, and apply that information to the first package they act on.
33 Debhelper programs should never modify the debian/postinst, debian/prerm,
34 etc scripts. Instead, they can add lines to debian/postinst.debhelper, etc.
35 The autoscript() function (see below) is one easy way to do this.
36 dh_installdeb is an exception, it will run after the other commands and
37 merge these modifications into the actual postinst scripts.
39 In general, files named debian/*.debhelper are internal to debhelper, and
40 their existence or use should not be relied on by external programs such as
41 the build process of a package.
43 Debhelper programs should default to doing exactly what policy says to do.
45 There are always exceptions. Just ask me.
47 Introducing Dh_Lib.pm:
50 Dh_Lib.pm is the library used by all debhelper programs to parse their
51 arguments and set some useful variables. It's not mandatory that your
52 program use Dh_Lib.pm, but it will make it a lot easier to keep it in sync
53 with the rest of debhelper if it does, so this is highly encouraged.
55 (There used to be a version of Dh_lib.pm that was a library of functions for
56 shell scripts. If you want to write a debhelper command that is a shell
57 script, I can dig up that old library for you. Only the perl one is
58 supported now, though.)
60 Use Dh_Lib.pm like this:
62 use Debian::Debhelper::Dh_Lib
65 The BEGIN block is there to make perl look for the module in all the right
68 The init() function causes Dh_lib to parse the command line and do some other
74 All debhelper programs should respond to certain arguments, such as -v, -i,
75 -a, and -p. To help you make this work right, Dh_Lib.pm handles argument
76 processing. Just call init().
78 After argument processing, some global variables are used to hold the
79 results; programs can use them later. These variables are elements of the
82 switch variable description
83 -v VERBOSE should the program verbosely output what it is
85 --no-act NO_ACT should the program not actually do anything?
86 -i,-a,-p,-N DOPACKAGES a space delimited list of the binary packages
87 to act on (in Dh_Lib.pm, this is an array)
88 -i DOINDEP set if we're acting on binary independent
90 -a DOARCH set if we're acting on binary dependent
92 -n NOSCRIPTS if set, do not make any modifications to the
93 package's postinst, postrm, etc scripts.
94 -X EXCLUDE exclude a something from processing (you
95 decide what this means for your program)
97 EXCLUDE_FIND same as DH_EXCLUDE, except all items are put
98 into a string in a way that they will make
99 find find them. (Use ! in front to negate
102 include conffiles. It's -x for obscure
104 -d D_FLAG you decide what this means to your program
105 -r R_FLAG you decide what this means to your program
106 -k K_FLAG you decide what this means to your program
107 -P TMPDIR package build directory (implies only one
108 package is being acted on)
109 -u U_PARAMS will be set to a string, that is typically
110 parameters your program passes on to some
111 other program. (This is an array)
112 -m M_PARAMS will be set to a string, you decide what it
113 means to your program
114 -l L_PARAMS will be set to a string, you decide what it
115 means to your program
116 -V V_FLAG will be set to a string, you decide what it
117 means to your program
118 -V V_FLAG_SET will be 1 if -V was specified, even if no
119 parameters were passed along with the -V
120 -A PARAMS_ALL generally means that additional command line
121 parameters passed to the program (other than
122 those processed here), will apply to all
123 binary packages the program acts on, not just
125 --init-script INIT_SCRIPT will be set to a string, which specifies an
126 init script name (probably only
127 dh_installinit will ever use this)
128 --sourcedir SOURCEDIR will be set to a string (probably only
129 dh_movefiles will ever use this)
130 --destdir DESTDIR will be set to a string (probably only
131 dh_builddeb will ever use this)
132 --filename FILENAME will be set to a string
133 --flavor FLAVOR will be set to a string (probably only
134 dh_installemacsen will ever use this)
135 --number PRIORITY will be set to a number (deprecated)
136 --priority PRIORITY will be set to a number
137 --name NAME a name to use for installed files, instead of
140 Any additional command line parameters that do not start with "-" will be
141 ignored, and you can access them later just as you normally would.
143 If you need a new command line option, just ask me, and I will add it.
148 The following keys are also set in the %dh hash when you call init():
150 MAINPACKAGE the name of the first binary package listed in
152 FIRSTPACKAGE the first package we were instructed to act on. This package
153 typically gets special treatment; additional arguments
154 specified on the command line may effect it.
159 Dh_Lib.pm also contains a number of functions you may find useful.
162 Pass this function an array that is a
163 shell command. It will run the command (unless $dh{NO_ACT} is set), and
164 if $dh{VERBOSE} is set, it will also output the command to stdout. You
165 should use this function for almost all commands your program performs
166 that manipulate files in the package build directories.
167 complex_doit($command)
168 Pass this function a string that is a shell command, it will run it
169 similarly to how doit() does. You can pass more complicated commands
170 to this (ie, commands involving piping redirection), however, you
171 have to worry about things like escaping shell metacharacters.
172 verbose_print($message)
173 Pass this command a string, and it will echo it if $dh{VERBOSE} is set.
175 Pass this command a string, it will output it to standard error and
178 Pass this command a string, and it will output it to standard error
179 as a warning message.
181 Pass this command the name of a binary package, it will return the
182 name of the tmp directory that will be used as this package's
183 package build directory. Typically, this will be "debian/package".
185 Pass this command a number, and if the current compatibility level
186 is less than or equal to that number, it will return true.
187 Looks at DH_COMPAT to get the compatibility level.
188 pkgfile($package, $basename)
189 Pass this command the name of a binary package, and the base name of a
190 file, and it will return the actual filename to use. This is used
191 for allowing debhelper programs to have configuration files in the
192 debian/ directory, so there can be one config file per binary
193 package. The convention is that the files are named
194 debian/package.filename, and debian/filename is also allowable for
195 the $dh{MAINPACKAGE}. If the file does not exist, nothing is returned.
197 Pass this command the name of a binary package, and it will return
198 the name to prefix to files in debian/ for this package. For the
199 $dh{MAINPACKAGE}, it returns nothing (there is no prefix), for the other
200 packages, it returns "package.".
202 Pass this command the name of a package, it returns 1 if the package
203 is a native debian package.
204 As a side effect, $dh{VERSION} is set to the version number of the
206 autoscript($package, $scriptname, $snippetname, $sedcommands)
208 - binary package to be affected
210 - filename of snippet
211 - sed commands to run on the snippet. Ie, s/#PACKAGE#/$PACKAGE/
213 This command automatically adds shell script snippets to a debian
214 maintainer script (like the postinst or prerm).
216 Return directory part of pathname.
218 Return base of pathname,
219 addsubstvar($package, $substvar, $deppackage, $verinfo, $remove)
220 This function adds a dependency on some package to the specified
221 substvar in a package's substvar's file. It needs all these
223 - binary package that gets the item
224 - name of the substvar to add the item to
225 - the package that will be depended on
226 - version info for the package (optional) (ie: ">= 1.1")
227 - if this last parameter is passed, the thing that would be added
228 is removed instead. This can be useful to ensure that a debhelper
229 command is idempotent. Note that without this parameter, if you
230 call the function twice with the same values it will only add one
231 item to the substvars file.
232 delsubstvar($package, $substvar)
233 This function removes the entire line for the substvar from the
234 package's shlibs file.
235 excludefile($filename)
236 This function returns true if -X has been used to ask for the file
239 -- Joey Hess <joeyh@debian.org>