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 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 or function()
command creates a new scope. A scope can also be created with the
block()
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)
and return(PROPAGATE)
commands
can be used as an alternate method to the set(PARENT_SCOPE)
and unset(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.
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 the FORCE
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 to cmake-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 to OLD
, 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 the set
command will add the
type. Furthermore, if the <type>
is PATH
or FILEPATH
and the <value>
provided on the command line is a relative path,
then the set
command will treat the path as relative to the
current working directory and convert it to an absolute path.
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.