Perhaps you will answer this question later in this series, but I am wondering how to see the exit code when I run main or some other binary from the command line. Especially when I compile and run with VS Code, the 0 from return 0 is not shown in the Terminal. Thanks!
another problem i faced is the return status gets modulo by 256, so when you return 256 in this case it's actually like you returned 0 and it show "success" even thought "ping" is misspelled
That's the limit of different exit codes on Linux it seems like. Although there looks to be ways to get the whole 32-bit integer that was returned by the process. Here are more details: stackoverflow.com/questions/179565/exitcodes-bigger-than-255-possible
The variable's name doesn't matter. And yes it's an integer. wstatus is simply the name of the function's parameter Here you can read up more on this topic: www.man7.org/linux/man-pages/man2/waitpid.2.html
Hello, can you tell me how I can receive a value from the child process when it receives a signal?! To clarify, the parent sends a signal to the child, and the child should return a pontuatuion (int). Ty, love your videos!
How to differentiate between the exit code 2 when received from the childprocess because ping was misspelled or the 2 that got returned from the ping program because the domain name was misspelled
You can simply check the return value of exec and then look at errno to find out what exactly happened for the first case and return a different error code than the one returned by ping. Here's more documentation on the topic: linux.die.net/man/2/execve
there is a way to execute a command and get the stdout and the exit code? i know i can get the output using popen(), but with this function i can't get the exit code any suggestion, or something I can start from
You could redirect the standard output to some pipe that then you can do whatever you want with in a parent process, here's a video on this: code-vault.net/lesson/43zvcsz6o1:1603732432539
But if you misspell the program name (pong instead of ping), you will get the "Could not find the program" message and also the "Success!" message, because the statusCode was 0 even though _execlp() could not find the program.
Interesting, I wonder why it doesn't return a proper error status code. Although, I guess, if you're executing anything after execlp, it already means the call failed and you can print an error message
so far I spent literally hours on your channel
not done yet
so next one goes now
your way of explaining really matches my ways of learning ;-)
1 hour trying to get error codes from a child process and in 5 minutes you gave me the answer. Love your channel :-D
Been battling with this issue all day today, your video has saved me. Thank you!!
Thank you, very useful courses, keep going sir.
You areee really helpingg sir thaanks
Amaizing--------------------------thanks a lot
🤩
Thanks 😁
Perhaps you will answer this question later in this series, but I am wondering how to see the exit code when I run main or some other binary from the command line. Especially when I compile and run with VS Code, the 0 from return 0 is not shown in the Terminal. Thanks!
If you run this in bash: echo $?
You should get the exit code of the previously executed command
@@CodeVault that is amazing thank you so much!
another problem i faced is the return status gets modulo by 256, so when you return 256 in this case it's actually like you returned 0 and it show "success" even thought "ping" is misspelled
That's the limit of different exit codes on Linux it seems like. Although there looks to be ways to get the whole 32-bit integer that was returned by the process. Here are more details: stackoverflow.com/questions/179565/exitcodes-bigger-than-255-possible
I am newbie, so just curious, the wstatus is just an integer right? Can it have a different name or is it a part of some nomenclature to follow?
The variable's name doesn't matter. And yes it's an integer. wstatus is simply the name of the function's parameter
Here you can read up more on this topic: www.man7.org/linux/man-pages/man2/waitpid.2.html
@@CodeVault Thank you for your response. I follow your videos meticulously and I just love them. Thank you for your quality content.
I want to create a c/c++ program to run MULTIPLE (say 10) c/c++ programs please help 🙏
Hello, can you tell me how I can receive a value from the child process when it receives a signal?! To clarify, the parent sends a signal to the child, and the child should return a pontuatuion (int). Ty, love your videos!
You can always call read inside the signal handler... although it's not recommended. Signals are not really designed to send/receive data.
How to differentiate between the exit code 2 when received from the childprocess because ping was misspelled or the 2 that got returned from the ping program because the domain name was misspelled
You can simply check the return value of exec and then look at errno to find out what exactly happened for the first case and return a different error code than the one returned by ping. Here's more documentation on the topic: linux.die.net/man/2/execve
there is a way to execute a command and get the stdout and the exit code?
i know i can get the output using popen(), but with this function i can't get the exit code
any suggestion, or something I can start from
You could redirect the standard output to some pipe that then you can do whatever you want with in a parent process, here's a video on this: code-vault.net/lesson/43zvcsz6o1:1603732432539
@@CodeVault thanks bro, you really help me!
giga brain
But if you misspell the program name (pong instead of ping), you will get the "Could not find the program" message and also the "Success!" message, because the statusCode was 0 even though _execlp() could not find the program.
Interesting, I wonder why it doesn't return a proper error status code. Although, I guess, if you're executing anything after execlp, it already means the call failed and you can print an error message
Thank you a l 000^1000 t!
thanks from 1337
I have compiled your code many times, child always returns 1 on success and failure both. I wonder why ...
Make sure you call execlp with valid parameters. Maybe you are missing "ping" from PATH
can you do video on semaphore code ?
Will look into it!
So the user can click that link and it takes them to google??
You mean the link google.com? Yes, of course.
i would be really surprised if your hight is 2m xd xd