# How to install a "generated" directory?
**URL:** https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267
**Category:** Code
**Created:** [May 24, 2020, 8:45pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267 "2020-05-24T20:45:51Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@fry](https://discourse.cmake.org/u/fry)
#### Post date: [May 24, 2020, 8:45pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267/1 "2020-05-24T20:45:51Z")
I have been trying to get better at CMake (currently reading _Professional CMake_ which is very good IMO) and I am trying to do the right thing in my build:
I have this program (which I am calling `black-box` because I don’t have control over it since it is provided part of some sdk) that needs to run during my build. This program takes an input and output directories as parameters. During the install phase, the output directory needs to be copied to some destination.
The program creates a bunch of files in `output directory`, one of them being `gui.lua`.
So I have the current setup:
```auto
set(INPUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/IN)
set(OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/OUT)
# it is possible that sources are not in the same folder so copying them in a single folder
file(COPY ${SOURCES} DESTINATION ${INPUT_DIR})
set(GUI_LUA_FILE ${OUTPUT_DIR}/gui.lua)
add_custom_command(
OUTPUT ${GUI_LUA_FILE}
COMMAND black-box ${INPUT_DIR} ${OUTPUT_DIR}
DEPENDS ${SOURCES}
)
add_custom_target(gen_dir DEPENDS ${GUI_LUA_FILE})
```
so now the issue is that I am not too sure how to express “_copy output directory during the install phase_” because `OUTPUT_DIR` is generated only if the target `gen_dir` is run. I also want the `black-box` command to run only when necessary (as it is a potentially a heavy command so it should not run unless any `SOURCES` changes).
I tried
```auto
install(
TARGETS gen_dir
DESTINATION ${INSTALL_DIR}
)
```
but this doesn’t work (not an executable, library, or module).
What would be the cmake way of doing this?
Thanks for the help
Yan
---
### Author:  [@marc.chevrier](https://discourse.cmake.org/u/marc.chevrier)
#### Post date: [May 25, 2020, 2:13pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267/2 "2020-05-25T14:13:12Z")
You have command `install(DIRECTORY ...)`.
---
### Author:  [@fry](https://discourse.cmake.org/u/fry)
#### Post date: [May 25, 2020, 2:17pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267/3 "2020-05-25T14:17:32Z")
Yes I have tried to use this command.
But in this case it is a directory that does not exist unless it gets generated. As far as I can tell there is no way to say: `install(DIRECTORY ... DEPENDS gen_dir)`. So if you run `cmake --build . --target install` then the directory will not be generated
---
### Author:  [@marc.chevrier](https://discourse.cmake.org/u/marc.chevrier)
#### Post date: [May 25, 2020, 2:35pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267/4 "2020-05-25T14:35:13Z")
The problem comes from the fact that you target `gen_dir` does not depend on target `all` so it is not built when you launch target `all`. Keyword `ALL` is required.
You must have:
```cmake
add_custom_target(gen_dir ALL DEPENDS ${GUI_LUA_FILE})
install (DIRECTORY ${OUTPUT_DIR} DESTINATION ${INSTALL_DIR})
```
---
### Author:  [@fry](https://discourse.cmake.org/u/fry)
#### Post date: [May 25, 2020, 2:42pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267/5 "2020-05-25T14:42:03Z")
I just tried this change and yes that fixed the issue. Running an install from scratch will also run the `gen_dir` target. Thanks for the help.
---
### Author:  [@jdoubleu](https://discourse.cmake.org/u/jdoubleu)
#### Post date: [July 10, 2026, 4:43pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267/6 "2026-07-10T16:43:17Z")
Stumbled upon the same issue. In my case, adding the `custom_target` to the `ALL` target is not an option. There might also be cases where there isn’t even a `custom_target` to begin with, just a `add_custom_command`.
I think the `install(FILE ...)` command should be clever enough what files to build first, just like any other target.
---
### Author:  [@craig.scott](https://discourse.cmake.org/u/craig.scott)
#### Post date: [July 10, 2026, 9:46pm UTC](https://discourse.cmake.org/t/how-to-install-a-generated-directory/1267/7 "2026-07-10T21:46:34Z")
> [@jdoubleu](#):
>
> I think the `install(FILE ...)` command should be clever enough what files to build first, just like any other target.
Doing an install can’t assume doing a build is possible. In fact, the more common usage these days of an install is likely to be part of running cpack, which is in turn likely to be invoked directly rather than as part of a build. While `make install` and `make package` are both still supported use cases, it’s not how I recommend folks do either operation. I normally steer folks away from directly installing other than to a staging area, which is easiest done using `cmake --install` because you can specify the staging location at install time with the `--prefix` option. Similarly, I recommend using `cpack` directly rather than `make package` because you again have more control over how packaging is done.
I recognise you probably are focused on doing `make install` right now (that’s the only use case where expecting “install” to build something would even be possible), but I’d encourage you to think of building and installing as separate steps. It will help you construct a better mental picture of a smoother workflow that will keep you closer to the happy path.