On 27. Aug, 2009, at 0:58, Swaroop Ramachandra wrote:
Hi,
I'm trying to do the following in my CMake file:
1. Generate a "xyz.txt" file
2. Compile a "generate.c" file to give out a "generate" binary in
my bin
directory.
3. Execute the "generate" binary (The binary just reads contents of
"xyz.txt" and creates a copy of "xyz.txt"using read() and write()
functions
in C)
The problem:
When I do a fresh build, 1 and 2 succeed. 3 fails with the following
error
*"bin/generate: Command not found"*
However, if I *re-run the build immediately* after, since the
"generate"
binary is already created, all 3 successfully execute. Here's a
snippet of
what I have written.
------------
------------
/*---- Code to generate xyz.txt -- Successfully generated each
time------*/
----------
---------
ADD_EXECUTABLE(generate ${CMAKE_CURRENT_SOURCE_DIR}/server/generate.c)
set(GEN ${CMAKE_BINARY_DIR}/bin/generate)
ADD_CUSTOM_COMMAND(
TARGET generate POST_BUILD
COMMAND ${GEN}
DEPENDS ${CMAKE_BINARY_DIR}/server/xyz.txt}
)
In my ADD_CUSTOM_COMMAND, I have specified POST_BUILD, which I
understood to
be that the command will be executed only after creation of the
"generate"
binary.
That's the wrong way to go about it. the TARGET form of the
add_custom_command is intended to "finish" the actual target. What you
want is something like this:
# no need for absolute paths...
add_executable(generate server/generate.c)
add_custom_command(
# tell cmake you want to generate xyz.c
OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/xyz.c
# using the generate program. cmake knows that "generate" refers to
the above target
COMMAND generate ${CMAKE_CURRENT_SOURCE_DIR}/xyz.txt
# only run if xyz.txt changed
DEPENDS xyz.txt
# tell to run in current binary dir
WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
# some nice comment in the output
COMMENT "Generating ${CMAKE_CURRENT_BINARY_DIR}/xyz.c"
VERBATIM
)
And then you simply use ${CMAKE_CURRENT_BINARY_DIR}/xyz.c in one of
your other targets. CMake will then know that it first needs to create
target "generate", then run the program on xyz.txt to create $
{CMAKE_CURRENT_BINARY_DIR}/xyz.c, and finally use that to build the
actual target.
HTH
Michael
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