Finding programs

Finding programs: find_executable looks a program up on the PATH, as a shell does before running it, find_companion looks beside the running program first, and is_executable tells whether a file can be run.

Source: runtime/process/find.pep

find_executable

find_executable(name: String): io.Path?

Returns the program name would run as a command: the first file named name in the directories PATH lists, in order, that this process may run. A name that holds a path separator is not looked up: it is returned when it names such a file itself. On Windows, a name with no extension also matches name.exe.

Parameters

• name — the program’s file name, such as "perf"

Returns

• the program’s path, or none when no directory on the PATH holds it

Example

import process;

main(): int {
    var git = process.find_executable("git");
    print(git.is_value() ? git.value().to_string() : "git is not installed");
    return 0;
}

is_executable

is_executable(path: io.Path): bool

Returns whether path is a file this process may run: on Linux and macOS, a file with an execute permission bit set; on Windows, any file.

Parameters

• path — the file to check

Returns

• true when path names a file that may be run

find_companion

find_companion(name: String): io.Path?

Returns the program name installed beside the running one, else the one find_executable finds on the PATH: how a tool finds the other tools of its suite, as pep-test finds pep-build. On Windows, .exe is added to name when looking beside the running program.

Parameters

• name — the program’s file name, such as "pep-build"

Returns

• the program’s path, or none when neither place holds it

Example

import process;

main(): int {
    var compiler = process.find_companion("pep-build");
    print(compiler.is_value() ? compiler.value().to_string() : "pep-build is not installed");
    return 0;
}