Add a custom build rule to the generated build system.
There are two main signatures for add_custom_command
.
The first signature is for adding a custom command to produce an output:
add_custom_command(OUTPUT output1 [output2 ...] COMMAND command1 [ARGS] [args1...] [COMMAND command2 [ARGS] [args2...] ...] [MAIN_DEPENDENCY depend] [DEPENDS [depends...]] [BYPRODUCTS [files...]] [IMPLICIT_DEPENDS <lang1> depend1 [<lang2> depend2] ...] [WORKING_DIRECTORY dir] [COMMENT comment] [DEPFILE depfile] [VERBATIM] [APPEND] [USES_TERMINAL])
This defines a command to generate specified OUTPUT
file(s). A target created in the same directory (CMakeLists.txt
file) that specifies any output of the custom command as a source file is given a rule to generate the file using the command at build time. Do not list the output in more than one independent target that may build in parallel or the two instances of the rule may conflict (instead use the add_custom_target()
command to drive the command and make the other targets depend on that one). In makefile terms this creates a new target in the following form:
OUTPUT: MAIN_DEPENDENCY DEPENDS COMMAND
The options are:
APPEND
COMMAND
and DEPENDS
option values to the custom command for the first output specified. There must have already been a previous call to this command with the same output. The COMMENT
, MAIN_DEPENDENCY
, and WORKING_DIRECTORY
options are currently ignored when APPEND is given, but may be used in the future.BYPRODUCTS
Specify the files the command is expected to produce but whose modification time may or may not be newer than the dependencies. If a byproduct name is a relative path it will be interpreted relative to the build tree directory corresponding to the current source directory. Each byproduct file will be marked with the GENERATED
source file property automatically.
Explicit specification of byproducts is supported by the Ninja
generator to tell the ninja
build tool how to regenerate byproducts when they are missing. It is also useful when other build rules (e.g. custom commands) depend on the byproducts. Ninja requires a build rule for any generated file on which another rule depends even if there are order-only dependencies to ensure the byproducts will be available before their dependents build.
The BYPRODUCTS
option is ignored on non-Ninja generators except to mark byproducts GENERATED
.
COMMAND
Specify the command-line(s) to execute at build time. If more than one COMMAND
is specified they will be executed in order, but not necessarily composed into a stateful shell or batch script. (To run a full script, use the configure_file()
command or the file(GENERATE)
command to create it, and then specify a COMMAND
to launch it.) The optional ARGS
argument is for backward compatibility and will be ignored.
If COMMAND
specifies an executable target name (created by the add_executable()
command) it will automatically be replaced by the location of the executable created at build time. If set, the CROSSCOMPILING_EMULATOR
executable target property will also be prepended to the command to allow the executable to run on the host. (Use the TARGET_FILE
generator expression
to reference an executable later in the command line.) Additionally a target-level dependency will be added so that the executable target will be built before any target using this custom command. However this does NOT add a file-level dependency that would cause the custom command to re-run whenever the executable is recompiled.
Arguments to COMMAND
may use generator expressions
. References to target names in generator expressions imply target-level dependencies, but NOT file-level dependencies. List target names with the DEPENDS
option to add file-level dependencies.
COMMENT
DEPENDS
Specify files on which the command depends. If any dependency is an OUTPUT
of another custom command in the same directory (CMakeLists.txt
file) CMake automatically brings the other custom command into the target in which this command is built. If DEPENDS
is not specified the command will run whenever the OUTPUT
is missing; if the command does not actually create the OUTPUT
then the rule will always run. If DEPENDS
specifies any target (created by the add_custom_target()
, add_executable()
, or add_library()
command) a target-level dependency is created to make sure the target is built before any target using this custom command. Additionally, if the target is an executable or library a file-level dependency is created to cause the custom command to re-run whenever the target is recompiled.
Arguments to DEPENDS
may use generator expressions
.
IMPLICIT_DEPENDS
C
and CXX
language scanners are supported. The language has to be specified for every file in the IMPLICIT_DEPENDS
list. Dependencies discovered from the scanning are added to those of the custom command at build time. Note that the IMPLICIT_DEPENDS
option is currently supported only for Makefile generators and will be ignored by other generators.MAIN_DEPENDENCY
DEPENDS
option but also suggests to Visual Studio generators where to hang the custom command. At most one custom command may specify a given source file as its main dependency.OUTPUT
GENERATED
source file property automatically. If the output of the custom command is not actually created as a file on disk it should be marked with the SYMBOLIC
source file property.USES_TERMINAL
Ninja
generator, this places the command in the console
pool
.VERBATIM
VERBATIM
is recommended as it enables correct behavior. When VERBATIM
is not given the behavior is platform specific because there is no protection of tool-specific special characters.WORKING_DIRECTORY
DEPFILE
.d
depfile for the Ninja
generator. A .d
file holds dependencies usually emitted by the custom command itself. Using DEPFILE
with other generators than Ninja is an error.The second signature adds a custom command to a target such as a library or executable. This is useful for performing an operation before or after building the target. The command becomes part of the target and will only execute when the target itself is built. If the target is already built, the command will not execute.
add_custom_command(TARGET <target> PRE_BUILD | PRE_LINK | POST_BUILD COMMAND command1 [ARGS] [args1...] [COMMAND command2 [ARGS] [args2...] ...] [BYPRODUCTS [files...]] [WORKING_DIRECTORY dir] [COMMENT comment] [VERBATIM] [USES_TERMINAL])
This defines a new command that will be associated with building the specified <target>
. The <target>
must be defined in the current directory; targets defined in other directories may not be specified.
When the command will happen is determined by which of the following is specified:
PRE_BUILD
PRE_BUILD
will be treated as PRE_LINK
.PRE_LINK
add_custom_target()
command.POST_BUILD
© 2000–2016 Kitware, Inc.
© 2000–2011 Insight Software Consortium
Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.7/command/add_custom_command.html