How do I get the path of a process in Unix / Linux?

Question

In a Windows environment there is an API to obtain the path which is running a process. Is there something similar in Unix / Linux?

Or is there some other way to do that in these environments?

Answer 1

On Linux, the symlink /proc/<pid>/exe has the path of the executable. Use the command readlink -f /proc/<pid>/exe to get the value.

On AIX, this file does not exist. You could compare cksum <actual path to binary> and cksum /proc/<pid>/object/a.out.

Answer 2

You can find the exe easily by these ways, just try it yourself.

• ll /proc/<PID>/exe
• pwdx <PID>
• lsof -p <PID> | grep cwd

Answer 3

All the answers were specific to Linux.

If you also need Unix, then you need this:

char * getExecPath (char * path,size_t dest_len, char * argv0)
{
    char * baseName = NULL;
    char * systemPath = NULL;
    char * candidateDir = NULL;

    /* the easiest case: we are on Linux */
    size_t buff_len;
    if (buff_len = readlink ("/proc/self/exe", path, dest_len - 1) != -1)
    {
        path [buff_len] = '\0';
        dirname (path);
        strcat  (path, "/");
        return path;
    }

    /* Ups... not on Linux, no guarantee */

    /* check if we have something like execve("foobar", NULL, NULL) */
    if (argv0 == NULL)
    {
        /* We surrender and give the current path instead */
        if (getcwd (path, dest_len) == NULL) return NULL;
        strcat  (path, "/");
        return path;
    }


    /* argv[0] */
    /* if dest_len < PATH_MAX may cause buffer overflow */
    if ((realpath (argv0, path)) && (!access (path, F_OK)))
    {
        dirname (path);
        strcat  (path, "/");
        return path;
    }

    /* Current path */
    baseName = basename (argv0);
    if (getcwd (path, dest_len - strlen (baseName) - 1) == NULL)
        return NULL;

    strcat (path, "/");
    strcat (path, baseName);
    if (access (path, F_OK) == 0)
    {
        dirname (path);
        strcat  (path, "/");
        return path;
    }

    /* Try the PATH. */
    systemPath = getenv ("PATH");
    if (systemPath != NULL)
    {
        dest_len--;
        systemPath = strdup (systemPath);
        for (candidateDir = strtok (systemPath, ":"); candidateDir != NULL; candidateDir = strtok (NULL, ":"))
        {
            strncpy (path, candidateDir, dest_len);
            strncat (path, "/", dest_len);
            strncat (path, baseName, dest_len);

            if (access(path, F_OK) == 0)
            {
                free (systemPath);
                dirname (path);
                strcat  (path, "/");
                return path;
            }
        }
        free(systemPath);
        dest_len++;
    }

    /* Again, someone has to use execve: we don’t know the executable name; we surrender and instead give the current path */
    if (getcwd (path, dest_len - 1) == NULL)
        return NULL;
    strcat  (path, "/");
    return path;
}

Answer 4

pwdx <process id>

This command will fetch the process path from where it is executing.

Answer 5

I use:

ps -ef | grep 786

Replace 786 with your PID or process name.

Answer 6

The below command searches for the name of the process in the running process list and redirects the pid to the pwdx command to find the location of the process.

ps -ef | grep "abc" |grep -v grep| awk '{print $2}' | xargs pwdx

Replace "abc" with your specific pattern.

Alternatively, if you could configure it as a function in .bashrc, you may find in handy to use if you need this to be used frequently.

ps1() { ps -ef | grep "$1" |grep -v grep| awk '{print $2}' | xargs pwdx; }

For example:

[admin@myserver:/home2/Avro/AvroGen]$ ps1 nifi

18404: /home2/Avro/NIFI

Answer 7

In Linux every process has its own folder in /proc. So you could use getpid() to get the pid of the running process and then join it with the path /proc to get the folder you hopefully need.

Here's a short example in Python:

import os
print os.path.join('/proc', str(os.getpid()))

Here's the example in ANSI C as well:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>


int
main(int argc, char **argv)
{
    pid_t pid = getpid();

    fprintf(stdout, "Path to current process: '/proc/%d/'\n", (int)pid);

    return EXIT_SUCCESS;
}

Compile it with:

gcc -Wall -Werror -g -ansi -pedantic process_path.c -oprocess_path 

Answer 8

There's no "guaranteed to work anywhere" method.

Step 1 is to check argv[0], if the program was started by its full path, this would (usually) have the full path. If it was started by a relative path, the same holds (though this requires getting teh current working directory, using getcwd().

Step 2, if none of the above holds, is to get the name of the program, then get the name of the program from argv[0], then get the user's PATH from the environment and go through that to see if there's a suitable executable binary with the same name.

Note that argv[0] is set by the process that execs the program, so it is not 100% reliable.

Answer 9

For AIX:

getPathByPid()
{
    if [[ -e /proc/$1/object/a.out ]]; then
        inode=`ls -i /proc/$1/object/a.out 2>/dev/null | awk '{print $1}'`
        if [[ $? -eq 0 ]]; then
            strnode=${inode}"$"
            strNum=`ls -li /proc/$1/object/ 2>/dev/null | grep $strnode | awk '{print $NF}' | grep "[0-9]\{1,\}\.[0-9]\{1,\}\."`
            if [[ $? -eq 0 ]]; then
                # jfs2.10.6.5869
                n1=`echo $strNum|awk -F"." '{print $2}'`
                n2=`echo $strNum|awk -F"." '{print $3}'`
                # brw-rw----    1 root     system       10,  6 Aug 23 2013  hd9var
                strexp="^b.*"$n1,"[[:space:]]\{1,\}"$n2"[[:space:]]\{1,\}.*$"    # "^b.*10, \{1,\}5 \{1,\}.*$"
                strdf=`ls -l /dev/ | grep $strexp | awk '{print $NF}'`
                if [[ $? -eq 0 ]]; then
                    strMpath=`df | grep $strdf | awk '{print $NF}'`
                    if [[ $? -eq 0 ]]; then
                        find $strMpath -inum $inode 2>/dev/null
                        if [[ $? -eq 0 ]]; then
                            return 0
                        fi
                    fi
                fi
            fi
        fi
    fi
    return 1
}

Courtesy Kiwy.

Answer 10

You can also get the path on GNU/Linux with (not thoroughly tested):

char file[32];
char buf[64];
pid_t pid = getpid();
sprintf(file, "/proc/%i/cmdline", pid);
FILE *f = fopen(file, "r");
fgets(buf, 64, f);
fclose(f);

If you want the directory of the executable for perhaps changing the working directory to the process's directory (for media/data/etc), you need to drop everything after the last /:

*strrchr(buf, '/') = '\0';
/*chdir(buf);*/

Answer 11

Find the path to a process name

#!/bin/bash
# @author Lukas Gottschall
PID=`ps aux | grep precessname | grep -v grep | awk '{ print $2 }'`
PATH=`ls -ald --color=never /proc/$PID/exe | awk '{ print $10 }'`
echo $PATH