[Solved-5 Solutions] Finding current executable's path without proc/self/exe - linux tutorial
Problem:
How to find current executable path without proc/self/exe ?
Solution 1:
Some OS-specific interfaces:
- Mac OS X: _NSGetExecutablePath() (man 3 dyld)
- Linux: readlink /proc/self/exe
- Solaris: getexecname()
- FreeBSD: sysctl CTL_KERN KERN_PROC KERN_PROC_PATHNAME -1
- FreeBSD if it has procfs: readlink /proc/curproc/file (FreeBSD doesn't have procfs by default)
- NetBSD: readlink /proc/curproc/exe
- DragonFly BSD: readlink /proc/curproc/file
Some shells, consist of bash and ksh, set the environment variable "_" to the full path of the executable before it is executed. In that case you can use getenv("_") to get it. However this is unreliable because not all shells do this, and it could be set to anything or be left over from a parent process which did not change it before executing your program.
Solution 2:
- Check out the whereami library from Gregory Pakosz (which has just a single C file).
- To get the full path to the current executable on a variety of platforms.
- It's available as a repo on github.
Solution 3:
To using either /proc/self/exe or argv[0] is using the information passed by the ELF interpreter, made available by glibc as such:
#include <stdio.h>
#include <sys/auxv.h>
int main(int argc, char **argv)
{
printf("%s\n", (char *)getauxval(AT_EXECFN));
return(0);
}Solution 4:
Isolating platform specific code with #ifdefs.
The other type would be to have clean #ifdef-less header wich contains function declarations and put the implementations in platform specific source files. For example, check out how Poco C++ library does something similar for their Environment class.
Solution 5:
- This code finds the executable's path in Windows, Linux, MacOS, Solaris or FreeBSD.
- To simplify the code but it's easy enough to remove.
- To use defines like _MSC_VER and __linux as the OS and compiler require.
#include <string>
#include <boost/predef/os.h>
#if (BOOST_OS_WINDOWS)
# include <stdlib.h>
#elif (BOOST_OS_SOLARIS)
# include <stdlib.h>
# include <limits.h>
#elif (BOOST_OS_LINUX)
# include <unistd.h>
# include <limits.h>
#elif (BOOST_OS_MACOS)
# include <mach-o/dyld.h>
#elif (BOOST_OS_BSD_FREE)
# include <sys/types.h>
# include <sys/sysctl.h>
#endif
/*
* Returns the full path to the currently running executable,
* or an empty string in case of failure.
*/
std::string getExecutablePath() {
#if (BOOST_OS_WINDOWS)
char *exePath;
if (_get_pgmptr(&exePath) != 0)
exePath = "";
#elif (BOOST_OS_SOLARIS)
char exePath[PATH_MAX];
if (realpath(getexecname(), exePath) == NULL)
exePath[0] = '\0';
#elif (BOOST_OS_LINUX)
char exePath[PATH_MAX];
ssize_t len = ::readlink("/proc/self/exe", exePath, sizeof(exePath));
if (len == -1 || len == sizeof(exePath))
len = 0;
exePath[len] = '\0';
#elif (BOOST_OS_MACOS)
char exePath[PATH_MAX];
uint32_t len = sizeof(exePath);
if (_NSGetExecutablePath(exePath, &len) != 0)
{
exePath[0] = '\0'; // buffer too small (!)
} else
{
// resolve symlinks, ., .. if possible
char *canonicalPath = realpath(exePath, NULL);
if (canonicalPath != NULL)
{
strncpy(exePath,canonicalPath,len);
free(canonicalPath);
}
}
#elif (BOOST_OS_BSD_FREE)
char exePath[2048];
int mib[4]; mib[0] = CTL_KERN; mib[1] = KERN_PROC; mib[2] = KERN_PROC_PATHNAME; mib[3] = -1;
size_t len = sizeof(exePath);
if (sysctl(mib, 4, exePath, &len, NULL, 0) != 0)
exePath[0] = '\0';
#endif
return std::string(exePath);
}The above version returns full paths including the executable name. If instead we want the path without the executable name, <#include boost/filesystem.hpp> and change the return statement :
return strlen(exePath)>0 ? boost::filesystem::path(exePath).remove_filename().make_preferred().string() : std::string();