Thread: Array splicing and extracting

Hello,

I am looking for an easy way to splice an array (full of commands). It is an array full of commands and pipes for the bash shell

Example, if I pass an array like the following into a function

array[0] = "ls"
array[1] = "-a"
array[2] = "|"
array[3] = "grep c"
array[4] = "|"
array[5] = "more"

What I want to do is extract array[0] and array[1], and execute them into a child process etc (open a pipe and use dup2 etc), continue until I find a pipe and extract array[3], and continue onwards.

Which string functions should I be using or simply an easier method. I have never been that good with C style strings and arrays.

Typically, array[0] will always be a command

Thankless task to write your own shell. It's probably a student task

I would suggest that you could probably send the arguments as a list to some suitable version of "exec" - there are many variants - I think "execv" or "execve" is the function you'd want. Unless you are doing this on a Windows system (or other "non-unix"), in which case I have no good idea on how you do that. (Concatenate the whole lot with "strcat", adding spaces where needed, and do "system(mylong_string_of_commands);" perhaps?

Edit: if you are using "exec", don't forget to do fork first...

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Mats

Yeah I know how to do the executing, I just need a little help on the array splicing first.

Edit: Student lab

Originally Posted by INFERNO2K

Yeah I know how to do the executing, I just need a little help on the array splicing first.

But you DON'T NEED to splice the array to use execv[e], as it takes a list of arguments already split up - so all you need to do is decide what is the command ("ls") and what is the argument(s) to that command ("-l"), and pass that as argv[] to exec. That's the whole point of my suggesting that you use this function.

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Mats

http://www.cplusplus.com/reference/clibrary/cstring/