How to check whether a command such as curl completed without error?

Question

I'm passing the function:

fillArrays(arrays);

Now, arrays is a 2 dimensional array. I declared the arrays like so:

int **arrays = new int*[NUM_OF_ARRAYS];
    arrays[0] = new int[128];
    arrays[1] = new int[512];
    arrays[2] = new int[2048];
    arrays[3] = new int[8192];
    arrays[4] = new int[32768];
    arrays[5] = new int[131072];
    arrays[6] = new int[524288];
    arrays[7] = new int[2097152];

Am I passing arrays into the following function correctly?

void fillArrays(int **arrays) {
    const int NUM_OF_ARRAYS = 8;
    for(int i = 0;i < NUM_OF_ARRAYS;i++) {
        switch(i) {
        case 0:
            for(int j = 0;j < 128;j++)
                arrays[i][j] = 1 + rand() % 2000;
            break;
        case 1:
            for(int j = 0;j < 512;j++)
                arrays[i][j] = 1 + rand() % 5000;
            break;
        case 2:
            for(int j = 0;j < 2048;j++)
                arrays[i][j] = 1 + rand() % 10000;
            break;
        case 3:
            for(int j = 0;j< 8192;j++)
                arrays[i][j] = 1 + rand() % 30000;
            break;
        case 4:
            for(int j = 0;j < 32768;j++)
                arrays[i][j] = 1 + rand() % 100000;
            break;
        case 5:
            for(int j = 0;j < 131072;j++)
                arrays[i][j] = 1 + rand() % 200000;
            break;
        case 6:
            for(int j = 0;j < 524288;j++)
                arrays[i][j] = 1 + rand() % 1000000;
            break;
        case 7:
            for(int j = 0;j < 2097152;j++)
                arrays[i][j] = 1 + rand() % 30000000;
            break;
        }
    }
}

Please let me know if you need any further information, thanks!

Solution 1

The simplest way is to store the response and compare it:

$ response=$(curl -X POST [email protected] server-URL);
$ if [ "Upload successful" == "${response}" ]; then … fi;

I haven't tested that. The syntax might be off, but that's the idea. I'm sure there are more sophisticated ways of doing it such as checking curl's exit code or something.

update

curl returns quite a few exit codes. I'm guessing a failed post might result in 55 Failed sending network data. So you could probably just make sure the exit code was zero by comparing to $? (Expands to the exit status of the most recently executed foreground pipeline.):

$ curl -X POST [email protected] server-URL;
$ if [ 0 -eq $? ]; then … fi;

Or if your command is relatively short and you want to do something when it fails, you could rely on the exit code as the condition in a conditional statement:

$ if curl --fail -X POST [email protected] server-URL; then
    # …(success)
else
    # …(failure)
fi;

I think this format is often preferred, but personally I find it less readable.

Solution 2

You might be able to use curl's --fail option, though you should test it once first.

man curl

-f, --fail (HTTP) Fail silently (no output at all) on server errors. This is mostly done to better enable scripts etc to better deal with failed attempts. In normal cases when an HTTP server fails to deliver a document, it returns an HTML document stating so (which often also describes why and more). This flag will pre‐ vent curl from outputting that and return error 22.

          This method is not fail-safe and there are occasions where  non-
          successful  response  codes  will  slip through, especially when
          authentication is involved (response codes 401 and 407).

In this way you could just do:

args="-X POST [email protected] server-URL"
curl -f $args && echo "SUCCESS!" ||
    echo "OH NO!"

Comments

[LeeNeverGup]

How exacly did you declare arrays?

[TravisG]

Very tempted to give "Yes, you do pass arrays correctly" as an answer :P

[Admin]

@LeeNeverGup I added my declarations to the question.

[Fiktik]

OT: Get rid of the outer loop - you loop over code that immediately disambiguates every iteration into separate code branch. This is pointless.

[StoryTeller - Unslander Monica]

I'm sorry, but are you faced with some sort of problem that you think resulted from passing the array? Is there another point to this question?

[Admin]

@Fiktik I don't understand, I want to assign each element of the 2d array, why does that not require an outer loop?

[SingerOfTheFall]

@sir_, you can get rid of it and the switch by replacing arrays[i][j] with arrays[0][j],arrays[1][j], and so on

[Fiktik]

@Sir_Blake_ Your outer loop iterates 8 times, you know this when writing the code and it will never change. Inside the loop, you choose which iteration are you in and do something special for each iteration. This is exactly the same as if you just did your eight different steps one after each other. Meaning, get rid of the loop, get rid of the switch and just have your eight inner loops one after each other. Of course you have to replace the indexing as SingerOfTheFall suggests. It would make your code more readable, and possibly more performant (optimizing compiler will do this anyway though)

[SingerOfTheFall]

they are accessible inside his function

[Artie]

@SingerOfTheFall, I believe that is what he said.

[cyqsimon]

This is probably the best practice in a scripting setting. For cURL exit codes see here: everything.curl.dev/usingcurl/returns