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.
32 The config file format should be as simple as possible, generally just a
33 list of files to act on.
35 Debhelper programs should never modify the debian/postinst, debian/prerm,
36 etc scripts. Instead, they can add lines to debian/postinst.debhelper, etc.
37 The autoscript() function (see below) is one easy way to do this.
38 dh_installdeb is an exception, it will run after the other commands and
39 merge these modifications into the actual postinst scripts.
41 In general, files named debian/*.debhelper are internal to debhelper, and
42 their existence or use should not be relied on by external programs such as
43 the build process of a package. These files will be deleted by dh_clean.
45 Debhelper programs should default to doing exactly what policy says to do.
47 There are always exceptions. Just ask me.
49 Introducing Dh_Lib.pm:
52 Dh_Lib.pm is the library used by all debhelper programs to parse their
53 arguments and set some useful variables. It's not mandatory that your
54 program use Dh_Lib.pm, but it will make it a lot easier to keep it in sync
55 with the rest of debhelper if it does, so this is highly encouraged.
57 (There used to be a version of Dh_lib.pm that was a library of functions for
58 shell scripts. If you want to write a debhelper command that is a shell
59 script, I can dig up that old library for you. Only the perl one is
60 supported now, though.)
62 Use Dh_Lib.pm like this:
64 use Debian::Debhelper::Dh_Lib
67 The BEGIN block is there to make perl look for the module in all the right
70 The init() function causes Dh_lib to parse the command line and do some other
76 All debhelper programs should respond to certain arguments, such as -v, -i,
77 -a, and -p. To help you make this work right, Dh_Lib.pm handles argument
78 processing. Just call init().
80 You can add support for additional options to your command by passing an
81 options hash to init(). The hash is then passed on the Getopt::Long to
82 parse the command line options. For example, to add a --foo option, which
85 init(options => { foo => \$dh{FOO} });
87 After argument processing, some global variables are used to hold the
88 results; programs can use them later. These variables are elements of the
91 switch variable description
92 -v VERBOSE should the program verbosely output what it is
94 --no-act NO_ACT should the program not actually do anything?
95 -i,-a,-p,-N DOPACKAGES a space delimited list of the binary packages
96 to act on (in Dh_Lib.pm, this is an array)
97 -i DOINDEP set if we're acting on binary independent
99 -a DOARCH set if we're acting on binary dependent
101 -n NOSCRIPTS if set, do not make any modifications to the
102 package's postinst, postrm, etc scripts.
103 -o ONLYSCRIPTS if set, only make modifications to the
104 package's scripts, but don't look for or
105 install associated files.
106 -X EXCLUDE exclude a something from processing (you
107 decide what this means for your program)
109 -X EXCLUDE_FIND same as EXCLUDE, except all items are put
110 into a string in a way that they will make
111 find find them. (Use ! in front to negate
112 that, of course) Note that this should
113 only be used inside complex_doit(), not in
115 -d D_FLAG you decide what this means to your program
116 -k K_FLAG used to turn on keeping of something
117 -P TMPDIR package build directory (implies only one
118 package is being acted on)
119 -u U_PARAMS will be set to a string, that is typically
120 parameters your program passes on to some
121 other program. (This is an array)
122 -V V_FLAG will be set to a string, you decide what it
123 means to your program
124 -V V_FLAG_SET will be 1 if -V was specified, even if no
125 parameters were passed along with the -V
126 -A PARAMS_ALL generally means that additional command line
127 parameters passed to the program (other than
128 those processed here), will apply to all
129 binary packages the program acts on, not just
131 --sourcedir SOURCEDIR will be set to a string
132 --destdir DESTDIR will be set to a string
133 --priority PRIORITY will be set to a number
134 --mainpackage MAINPACKAGE controls which package is treated as the
135 main package to act on
136 --name NAME a name to use for installed files, instead of
138 --error-handler ERROR_HANDLER a function to call on error
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.
146 The following keys are also set in the %dh hash when you call init():
148 MAINPACKAGE the name of the first binary package listed in
150 FIRSTPACKAGE the first package we were instructed to act on. This package
151 typically gets special treatment; additional arguments
152 specified on the command line may effect it.
157 Dh_Lib.pm also contains a number of functions you may find useful.
160 Pass this function an array that is a
161 shell command. It will run the command (unless $dh{NO_ACT} is set), and
162 if $dh{VERBOSE} is set, it will also output the command to stdout. You
163 should use this function for almost all commands your program performs
164 that manipulate files in the package build directories.
165 complex_doit($command)
166 Pass this function a string that is a shell command, it will run it
167 similarly to how doit() does. You can pass more complicated commands
168 to this (ie, commands involving piping redirection), however, you
169 have to worry about things like escaping shell metacharacters.
170 verbose_print($message)
171 Pass this command a string, and it will echo it if $dh{VERBOSE} is set.
173 Pass this command a string, it will output it to standard error and
176 Pass this command a string, and it will output it to standard error
177 as a warning message.
179 Pass this command the name of a binary package, it will return the
180 name of the tmp directory that will be used as this package's
181 package build directory. Typically, this will be "debian/package".
183 Pass this command a number, and if the current compatibility level
184 is less than or equal to that number, it will return true.
185 Looks at DH_COMPAT to get the compatibility level.
186 pkgfile($package, $basename)
187 Pass this command the name of a binary package, and the base name of a
188 file, and it will return the actual filename to use. This is used
189 for allowing debhelper programs to have configuration files in the
190 debian/ directory, so there can be one config file per binary
191 package. The convention is that the files are named
192 debian/package.filename, and debian/filename is also allowable for
193 the $dh{MAINPACKAGE}. If the file does not exist, nothing is returned.
195 Pass this command the name of a binary package, and it will return
196 the name to prefix to files in debian/ for this package. For the
197 $dh{MAINPACKAGE}, it returns nothing (there is no prefix), for the other
198 packages, it returns "package.".
200 Pass this command the name of a package, it returns 1 if the package
201 is a native debian package.
202 As a side effect, $dh{VERSION} is set to the version number of the
204 autoscript($package, $scriptname, $snippetname, $sedcommands)
206 - binary package to be affected
208 - filename of snippet
209 - sed commands to run on the snippet. Ie, s/#PACKAGE#/$PACKAGE/
211 This command automatically adds shell script snippets to a debian
212 maintainer script (like the postinst or prerm).
213 Note that in v6 mode and up, the snippets are added in reverse
214 order for the removal scripts.
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 Returns true if the package is marked as a udeb in the control
241 udeb_filename($package)
242 Returns the filename of the udeb package.
244 Returns a list of packages in the control file.
245 Must pass "arch" or "indep" or "same" to specify arch-dependent or
246 -independent or same arch packages. If nothing is specified, returns all
248 As a side effect, populates %package_arches and %package_types with
249 the types of all packages (not only those returned).
251 Prevent logging the program's successful finish to
252 debian/*debhelper.log
254 -- Joey Hess <joeyh@debian.org>