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Programming-Idioms

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  • Rust

Idiom #107 Get folder containing current program

Assign to string dir the path of the folder containing the currently running executable.
(This is not necessarily the working directory, though.)

let dir = std::env::current_exe()?
    .canonicalize()
    .expect("the current exe should exist")
    .parent()
    .expect("the current exe should be a file")
    .to_string_lossy()
    .to_owned();

Rust doesn't represent paths as Strings, so we need to convert the Path returned from Path::parent. This code chooses to do this lossily, replacing characters it doesn't recognize with �
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <linux/limits.h>
#include <libgen.h>

int main()
{
    char exe[PATH_MAX], real_exe[PATH_MAX];
    ssize_t r;
    char *dir;

    if ((r = readlink("/proc/self/exe", exe, PATH_MAX)) < 0)
      exit(1);
    if (r == PATH_MAX)
	r -= 1;
    exe[r] = 0;
    if (realpath(exe, real_exe) == NULL)
	exit(1);
    dir = dirname(real_exe);
    puts(dir);
}

If the executable file that the current process is executing can be found searching $PATH, this is easier, but the general case can still be handled by examining where the symlink file /proc/self/exe points to.
New implementation...
< > ⌨
programming-idioms.org 
let dir = std::env::current_exe()?
    .canonicalize()
    .expect("the current exe should exist")
    .parent()
    .expect("the current exe should be a file")
    .to_string_lossy()
    .to_owned();
int main()
{
    char exe[PATH_MAX], real_exe[PATH_MAX];
    ssize_t r;
    char *dir;

    if ((r = readlink("/proc/self/exe", exe, PATH_MAX)) < 0)
      exit(1);
    if (r == PATH_MAX)
	r -= 1;
    exe[r] = 0;
    if (realpath(exe, real_exe) == NULL)
	exit(1);
    dir = dirname(real_exe);
    puts(dir);
}

dir = AppDomain.CurrentDomain.BaseDirectory;

void main(string[] args) {
    string dir = args[0].dirName;
}
programPath := os.Args[0]
absolutePath, err := filepath.Abs(programPath)
if err != nil {
	return err
}
dir := filepath.Dir(absolutePath)
dir <- takeDirectory `fmap` getExecutablePath
dir = unsafePerformIO (takeDirectory `fmap` getExecutablePath)
const dir = path.resolve();
const dir = __dirname;
dir = arg[1]
$dir = realpath(dirname(__FILE__));
dir := extractfilepath(paramstr(0));
dir := GetCurrentDir;
my $dir = path($EXECUTABLE_NAME)->parent;

dir = os.path.dirname(os.path.abspath(__file__))
dir = str(Path(__file__).parent)
dir = __dir__