1 This file documents things you should know to write a new debhelper program.
6 There are lots of debhelper commands. To make the learning curve shallower,
7 I want them all to behave in a standard manner:
9 All debhelper programs have names beginning with "dh_". This is so we don't
10 pollute the name space too much.
12 Debhelper programs should never output anything to standard output except
13 error messages, important warnings, and the actual commands they run that
14 modify files under debian/ and debian/tmp, etc (this last only if they are
15 passed -v, and if you output the commands, you should indent them with 1 tab).
16 This is so we don't have a lot of noise output when all the debhelper commands
17 in a debian/rules are run, so the important stuff is clearly visible.
19 Debhelper programs should accept the options, -v, -i, -a, -p, --no-act, and
20 -P, and any long forms of these options, like --verbose . If necessary, the
21 options may be ignored.
23 If debhelper commands need config files, they should use
24 debian/package.filename as the name of the config file (replace filename
25 with whatever your command wants), and debian/filename should also be
26 checked for config information for the first binary package in
27 debian/control. Also, debhelper commands should accept the same sort of
28 information that appears in the config files, on their command lines, if
29 possible, and apply that information to the first package they act on.
31 Debhelper programs should never modify the debian/postinst, debian/prerm,
32 etc scripts, instead, they can add lines to debian/postinst.debhelper, etc.
33 The autoscript() function (see below) is one easy way to do this.
34 dh_installdeb is an exception, it will run after the other commands and
35 merge these modifications into the actual postinst scripts.
37 Debhelper programs should default to doing exactly what policy says to do.
39 There are always exceptions. Just ask me.
41 Introducing Dh_Lib.pm:
44 Dh_lib.pm is the library used by all debhelper programs to parse their
45 arguments and set some useful variables. It's not mandatory that your
46 program use Dh_lib.pm, but it will make it a lot easier to keep it in sync
47 with the rest of debhelper if it does, so this is highly encouraged.
49 (There used to be a version of Dh_lib.pm that was a library of functions for
50 shell scripts. If you want to write a debhelper command that is a shell
51 script, I can dig up that old library for you. Only the perl one is
52 supported now, though.)
54 Use Dh_lib.pm like this:
56 BEGIN { push @INC, "debian", "/usr/share/debhelper" }
60 The BEGIN block is there to make perl look for the module in all the right
63 The init() function in the perl version. This causes Dh_lib to
64 parse the command line and do some other initialization tasks.
69 All debhelper programs should respond to certain arguments, such as -v, -i,
70 -a, and -p. To help you make this work right, Dh_Lib.pm handles argument
71 processing. Just call init().
73 After argument processing, some global variables are used to hold the
74 results; programs can use them later. These variables are elements of the
77 switch variable description
78 -v VERBOSE should the program verbosely output what it is
80 --no-act NO_ACT should the program not actually do anything?
81 -i,-a,-p,-N DOPACKAGES a space delimited list of the binary packages
82 to act on (in Dh_Lib.pm, this is an array)
83 -i,-p,-N DOINDEP a space delimited list of the binary independent
85 -a,-p,-N DOARCH a space delimited list of the binary dependent
87 -n NOSCRIPTS if set, do not make any modifications to the
88 package's postinst, postrm, etc scripts.
89 -X EXCLUDE exclude a something from processing (you
90 decide what this means for your program)
92 EXCLUDE_FIND same as DH_EXCLUDE, except all items are put
93 into a string in a way that they will make
94 find find them. (Use ! in front to negate
97 include conffiles. It's -x for obscure
99 -d D_FLAG you decide what this means to your program
100 -r R_FLAG you decide what this means to your program
101 -k K_FLAG you decide what this means to your program
102 -P TMPDIR package build directory (implies only one
103 package is being acted on)
104 -u U_PARAMS will be set to a string, that is typically
105 parameters your program passes on to some
106 other program. (This is an array)
107 -m M_PARAMS will be set to a string, you decide what it
108 means to your program
109 -l L_PARAMS will be set to a string, you decide what it
110 means to your program
111 -V V_FLAG will be set to a string, you decide what it
112 means to your program
113 -V V_FLAG_SET will be 1 if -V was specified, even if no
114 parameters were passed along with the -V
115 -A PARAMS_ALL generally means that additional command line
116 parameters passed to the program (other than
117 those processed here), will apply to all
118 binary packages the program acts on, not just
120 --init-script INIT_SCRIPT will be set to a string, which specifies an
121 init script name (probably only
122 dh_installinit will ever use this)
123 --sourcedir SOURCEDIR will be set to a string (probably only
124 dh_movefiles will ever use this)
125 --destdir DESTDIR will be set to a string (probably only
126 dh_builddeb will ever use this)
127 --flavor FLAVOR will be set to a string (probably only
128 dh_installemacsen will ever use this)
129 --number NUMBER will be set to a number
131 Any additional command line parameters that do not start with "-" will be
132 ignored, and you can access them later just as you normally would.
134 If you need a new command line option, just ask me, and I will add it.
139 The following keys are also set in the %dh hash when you call init():
141 MAINPACKAGE the name of the first binary package listed in
143 FIRSTPACKAGE the first package we were instructed to act on. This package
144 typically gets special treatment, additional arguments
145 specified on the command line may effect it.
150 Dh_Lib.pm also contains a number of functions you may find useful.
153 Pass this function an array that is a
154 shell command. It will run the command (unless $dh{NO_ACT} is set), and
155 if $dh{VERBOSE} is set, it will also output the command to stdout. You
156 should use this function for almost all commands your program performs
157 that manipulate files in the package build directories.
159 Pass this function a string that is a shell command, it will run it
160 similarly to how doit() does. You can pass more complicated commands
161 to this (ie, commands involving piping redirection), however, you
162 have to worry about things like escaping shell metacharacters.
164 Pass this command a string, and it will echo it if $dh{VERBOSE} is set.
166 Pass this command a string, it will output it to standard error and
169 Pass this command a string, and it will output it to standard error
170 as a warning message.
172 Pass this command the name of a binary package, it will return the
173 name of the tmp directory that will be used as this package's
174 package build directory. Typically, this will be "debian/tmp" or
177 Pass this command a number, and if the current compatability level
178 equals that number, it will return true. Looks at DH_COMPAT to get
179 the compatability level.
181 Pass this command the name of a binary package, and the base name of a
182 file, and it will return the actual filename to use. This is used
183 for allowing debhelper programs to have configuration files in the
184 debian/ directory, so there can be one config file per binary
185 package. The convention is that the files are named
186 debian/package.filename, and debian/filename is also allowable for
187 the $dh{MAINPACKAGE}. If the file does not exist, nothing is returned.
189 Pass this command the name of a binary package, and it will return
190 the name to prefix to files in debian/ for this package. For the
191 $dh{MAINPACKAGE}, it returns nothing (there is no prefix), for the other
192 packages, it returns "package.".
194 Pass this command the name of a package, it returns 1 if the package
195 is a native debian package.
196 As a side effect, $dh{VERSION} is set to the version number of the
200 - binary package to be affected
202 - filename of snippet
203 - sed commands to run on the snippet. Ie, s/#PACKAGE#/$PACKAGE/
205 This command automatically adds shell script snippets to a debian
206 maintainer script (like the postinst or prerm).
208 -- Joey Hess <joeyh@debian.org>