CMake is a build system generator that allows us to configure, build, and test projects. Among its many commands and functions, the file() command plays a crucial role in file-related operations within scripts. In this Answer, we’ll delve into the meaning and usage of the file() command in CMake.
Note: To learn more about CMake, visit the Modern CMake for C++ course on Educative.
The CMake’s file() command is a versatile tool for manipulating files, directories, and file properties within CMake scripts. It provides a wide range of functionalities, which are listed below:
Reading file contents
Writing to files
Creating directories
Setting file permissions
Retrieving file size
Manipulating file properties
Let’s explore some common use cases of the file() command with some coding examples.
Consider the code below:
file(READ "example.txt" content)
message("File contents: ${content}")This can be explained as follows:
Line 1: We use the file() method to read the example.txt file’s content.
Line 2: We display the contents of the file.
This illustrates how files can be read. To write to files, replace the code in the script with the following and run again:
file(WRITE "output.txt" "Hello, World!")file(READ "output.txt" content)message("File contents: ${content}")
The first line writes to a new file output.txt with the file() method, which we then read and display.
We can also create directories using this method. Replace the code in the script above with the following code:
file(MAKE_DIRECTORY "my_dir")
Now enter ls in the terminal, and we can see the new directory my_dir created.
Similarly, we can also display the size of a specific file with the use of SIZE. Replace the code in the script to the one below:
file(SIZE "example.txt" size)message("File size: ${content}")
To conclude, the file() command in CMake is used for performing file-related operations within CMake scripts. By mastering the usage of the file() command, we can streamline our build processes and ensure smooth configurations in CMake.
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