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Execlp() function in C

The C programming language offers many functions that enable programmers to complete a variety of jobs successfully. Execlp() is an effective function, which enables you to run another program from within your C program. In this article, you will discuss the execlp() function's complexities, syntax, usage, examples, and outputs.

The C standard library's exec family of functions includes the execlp() function. It enables you to switch out the current process image for a different one that is specified by the given program path. This function comes in handy when you wish to run outside programs from a C program.


The execlp() function has the following syntax:

execlp()'s parameters are as follows:

the location of the program you want to run in a file.

arg0, ...: A list of optional arguments for the program, with a null pointer (i.e., (char *)0) as the last argument to end the list.

The function wants the program to be located in one of the directories provided in the PATH environment variable, and it's vital to notice that the arguments are passed as strings.

Example of execlp() function

Let's take at a straightforward example to understand better how execlp() functions. Let's say you want our C program to run the ls command, which displays a directory's contents. Here's how you can make it happen:


The program's output will show thorough details on the files and directories in the current directory, much like the ls -l command in the terminal does.

Executing ls command...
total 597964
drwxr-xr-x 2 root root      4096 Apr 13 12:17 apache2
drwxrwxrwt 1 root root      4096 Apr 13 12:17 lock
drwxr-xr-x 2 root root      4096 Apr 13 12:11 log
drwxr-xr-x 2 root root      4096 Mar  8 02:05 mount
drwxr-xr-x 1 root root      4096 Apr 13 12:19 node_modules
-rwxr-xr-x 1 root root  75175505 Apr 13 12:10 programiz-oc
-rwxr-xr-x 1 root root     35040 Apr 13 12:10 pty.node
drwxr-xr-x 3 root root      4096 May 24 17:20 secrets
drwxr-xr-x 2 root root      4096 Apr 13 12:11 sendsigs.omit.d
lrwxrwxrwx 1 root root         8 Apr 13 12:11 shm -> /dev/shm
drwxr-xr-x 3 root root      4096 Apr 13 12:18 swift-5.7.2-RELEASE-ubuntu22.04
-rw-r--r-- 1 root root 537055150 Apr 13 12:18 swift.tar.gz
drwxr-xr-x 1 root root      4096 Apr 13 12:11 systemd
drwxr-xr-x 2 root root      4096 Apr 13 12:11 user


The required header files are first included in this example. After that, in the main() function, we print a message to show that the ls command has been executed. Finally, you run the execlp() function, supplying the desired arguments ("-l" to list in long format) and the program name ("ls"). By supplying a null pointer, the argument list is ended.

The output of the ls command will appear in the console when we compile and run the program execlp() function will swap out the current process image for the ls command. You can see the file and directory details in the output from the previous command, including permissions, ownership, size, and modification date.

The execlp() function gives the tools to programmers to create complex and flexible applications since it allows them to run external programs and replace the active process image. It can be used in conjunction with other C functions and methods to build intricate workflows, automate jobs, and improve the usefulness of your programs. So, embrace execlp()'s potential to open a world of possibilities for your C programming works.


The C programming language's execlp() function is a strong tool that makes it simple to run other programs. You can successfully integrate external functions into the C programs by comprehending its syntax, usage, and behavior. The ability to swap out the current process picture for a fresh one offers a tone of freedom and countless development options.

We investigated the execlp() function's nuances throughout this blog post and gave detailed instructions on how to use it. We talked about the syntax, gave a real-world example, and looked at the desired results. With this information, you may securely add the execlp() function to your code and easily run external programs.

Don't forget that the C language has a family of functions called exec, which includes the execlp() function. There are further variations, such execvp(), execle(), and others, each of which has a particular function. You can become a better C programmer by learning more about these functions.

By utilizing the execlp() function to its full potential, you may develop more durable and dynamic programs that communicate with the underlying operating system, allowing you to utilize existing tools and utilities effortlessly. Take advantage of the execlp() function to advance your C programming abilities..

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