Hi,

I am trying to write a shell terminal in c and I have a simple problem here.

Assume I have an array of char like char array[500]="ls -l -Q";

I need to parse these commands to a pointer array like **args

So I need to know how many arguments there are in the array to malloc the args. First I thought that I may use the space character but the form may not always be like "ls -l -Q", there may be many space characters between them.

Is there a simple way of doing this? If not I will try to reform the array, adjusting the number of space characters to 1 between strings.

You probably want to look at the C function strtok()
--- rod.

Granted, it's not directly a part of your original question, but the idea did occur to me: what happens when a command allows arguments to be lumped together? Example: tar zcvf archive.tgz directory/

taylor_venable makes a good point. I think, after seeing that the man page for strtok() says "never use this function", the definitive source for command line argument parsing woudl be the source code for getopt().

--- rod.

I think getopt is for the application to process args after they have been nicely split up by the shell into the argv array.

Since the OP is writing a shell this function is not really applicable. strtok() could work if you only want to split based on spaces, as soon as you want the more complicated stuff like quotes, escaping backslashes and stuff it's completely useless.

I imagine this is being written for learning purposes, so a function that parses the line for you maybe isn't what's needed here (I'm sure you can find one on the 'net). I'd use a simple for loop and have a switch statement for the "interesting" characters (ie space, ', ", \, |, >, etc). I wonder whether it would be better to count the tokens first or resize the array as you go along?

this sort of thing I would bin scanf and use
fgets to grab the whole line then
parse it after
do man strtok you'll find there are a whole load of string splitting functions
to use.

Thanks everyone.

I handled it with the simplest way; loops and switches

I checked strtok and getopt also. Getopt is for the part after I parse the command line into argc. So I could'nt use it in this case.

Now I need to find how to use "cd" command within an exec call and opened a new topic for it :=)