Execute one or more child processes.

execute_process(COMMAND <cmd1> [<arguments>]
                [COMMAND <cmd2> [<arguments>]]...
                [WORKING_DIRECTORY <directory>]
                [TIMEOUT <seconds>]
                [RESULT_VARIABLE <variable>]
                [RESULTS_VARIABLE <variable>]
                [OUTPUT_VARIABLE <variable>]
                [ERROR_VARIABLE <variable>]
                [INPUT_FILE <file>]
                [OUTPUT_FILE <file>]
                [ERROR_FILE <file>]
                [COMMAND_ECHO <where>]
                [ENCODING <name>]
                [COMMAND_ERROR_IS_FATAL <ANY|LAST>])

Runs the given sequence of one or more commands.

Commands are executed concurrently as a pipeline, with the standard output of each process piped to the standard input of the next. A single standard error pipe is used for all processes.



A child process command line.

CMake executes the child process using operating system APIs directly:

  • On POSIX platforms, the command line is passed to the child process in an argv[] style array.

  • On Windows platforms, the command line is encoded as a string such that child processes using CommandLineToArgvW will decode the original arguments.

No intermediate shell is used, so shell operators such as > are treated as normal arguments. (Use the INPUT_*, OUTPUT_*, and ERROR_* options to redirect stdin, stdout, and stderr.)

If a sequential execution of multiple commands is required, use multiple execute_process() calls with a single COMMAND argument.


The named directory will be set as the current working directory of the child processes.


After the specified number of seconds (fractions allowed), all unfinished child processes will be terminated, and the RESULT_VARIABLE will be set to a string mentioning the "timeout".


The variable will be set to contain the result of last child process. This will be an integer return code from the last child or a string describing an error condition.


New in version 3.10.

The variable will be set to contain the result of all processes as a semicolon-separated list, in order of the given COMMAND arguments. Each entry will be an integer return code from the corresponding child or a string describing an error condition.


The variable named will be set with the contents of the standard output and standard error pipes, respectively. If the same variable is named for both pipes their output will be merged in the order produced.


The file named will be attached to the standard input of the first process, standard output of the last process, or standard error of all processes, respectively.

New in version 3.3: If the same file is named for both output and error then it will be used for both.


The standard output or standard error results will be quietly ignored.


New in version 3.15.

The command being run will be echo'ed to <where> with <where> being set to one of STDERR, STDOUT or NONE. See the CMAKE_EXECUTE_PROCESS_COMMAND_ECHO variable for a way to control the default behavior when this option is not present.


New in version 3.8.

On Windows, the encoding that is used to decode output from the process. Ignored on other platforms. Valid encoding names are:


Perform no decoding. This assumes that the process output is encoded in the same way as CMake's internal encoding (UTF-8). This is the default.


Use the current active console's codepage or if that isn't available then use ANSI.


Use the ANSI codepage.


Use the original equipment manufacturer (OEM) code page.

UTF8 or UTF-8

Use the UTF-8 codepage.

New in version 3.11: Accept UTF-8 spelling for consistency with the UTF-8 RFC naming convention.


New in version 3.18.

The standard output or standard error will not be exclusively redirected to the configured variables.

The output will be duplicated, it will be sent into the configured variables and also on standard output or standard error.

This is analogous to the tee Unix command.


New in version 3.19.

The option following COMMAND_ERROR_IS_FATAL determines the behavior when an error is encountered:

ANY If any of the commands in the list of commands fail, the execute_process() command halts with an error.

LAST If the last command in the list of commands fails, the execute_process() command halts with an error. Commands earlier in the list will not cause a fatal error.

If more than one OUTPUT_* or ERROR_* option is given for the same pipe the precedence is not specified. If no OUTPUT_* or ERROR_* options are given the output will be shared with the corresponding pipes of the CMake process itself.

The execute_process() command is a newer more powerful version of exec_program(), but the old command has been kept for compatibility. Both commands run while CMake is processing the project prior to build system generation. Use add_custom_target() and add_custom_command() to create custom commands that run at build time.