set¶
Set a normal, cache, or environment variable to a given value. See the cmake-language(7) variables documentation for the scopes and interaction of normal variables and cache entries.
Signatures of this command that specify a <value>...
placeholder
expect zero or more arguments. Multiple arguments will be joined as
a semicolon-separated list to form the
actual variable value to be set.
Set Normal Variable¶
- set(<variable> <value>... [PARENT_SCOPE])¶
Set or unset
<variable>
in the current function or directory scope:If at least one
<value>...
is given, set the variable to that value.If no value is given, unset the variable. This is equivalent to
unset(<variable>)
.
If the
PARENT_SCOPE
option is given the variable will be set in the scope above the current scope. Each new directory orfunction()
command creates a new scope. A scope can also be created with theblock()
command.set(PARENT_SCOPE)
will set the value of a variable into the parent directory, calling function, or encompassing scope (whichever is applicable to the case at hand). The previous state of the variable's value stays the same in the current scope (e.g., if it was undefined before, it is still undefined and if it had a value, it is still that value).The
block(PROPAGATE)
andreturn(PROPAGATE)
commands can be used as an alternate method to theset(PARENT_SCOPE)
andunset(PARENT_SCOPE)
commands to update the parent scope.
Note
When evaluating Variable References of the form ${VAR}
, CMake
first searches for a normal variable with that name. If no such normal
variable exists, CMake will then search for a cache entry with that name.
Because of this, unsetting a normal variable can expose a cache variable
that was previously hidden. To force a variable reference of the form
${VAR}
to return an empty string, use set(<variable> "")
, which
clears the normal variable but leaves it defined.
Set Cache Entry¶
- set(<variable> <value>... CACHE <type> <docstring> [FORCE])¶
Sets the given cache
<variable>
(cache entry). Since cache entries are meant to provide user-settable values this does not overwrite existing cache entries by default. Use theFORCE
option to overwrite existing entries.The
<type>
must be specified as one of:BOOL
Boolean
ON/OFF
value.cmake-gui(1)
offers a checkbox.FILEPATH
Path to a file on disk.
cmake-gui(1)
offers a file dialog.PATH
Path to a directory on disk.
cmake-gui(1)
offers a file dialog.STRING
A line of text.
cmake-gui(1)
offers a text field or a drop-down selection if theSTRINGS
cache entry property is set.INTERNAL
A line of text.
cmake-gui(1)
does not show internal entries. They may be used to store variables persistently across runs. Use of this type impliesFORCE
.
The
<docstring>
must be specified as a line of text providing a quick summary of the option for presentation tocmake-gui(1)
users.If the cache entry does not exist prior to the call or the
FORCE
option is given then the cache entry will be set to the given value.Note
The content of the cache variable will not be directly accessible if a normal variable of the same name already exists (see rules of variable evaluation). If policy
CMP0126
is set toOLD
, any normal variable binding in the current scope will be removed.It is possible for the cache entry to exist prior to the call but have no type set if it was created on the
cmake(1)
command line by a user through the-D<var>=<value>
option without specifying a type. In this case theset
command will add the type. Furthermore, if the<type>
isPATH
orFILEPATH
and the<value>
provided on the command line is a relative path, then theset
command will treat the path as relative to the current working directory and convert it to an absolute path.
Set Environment Variable¶
- set(ENV{<variable>} [<value>])¶
Sets an
Environment Variable
to the given value. Subsequent calls of$ENV{<variable>}
will return this new value.This command affects only the current CMake process, not the process from which CMake was called, nor the system environment at large, nor the environment of subsequent build or test processes.
If no argument is given after
ENV{<variable>}
or if<value>
is an empty string, then this command will clear any existing value of the environment variable.Arguments after
<value>
are ignored. If extra arguments are found, then an author warning is issued.