Returning the actual value from a simple unix cmd

[cptk]

Is there a simpler way/method to get the return value from a unix cmd then to use the following method:

FILE *in;
char cmd[5] = "pwd";
char buf[100];

in = popen(cmd, "r");
fgets(buf,100,in);
/* or use some form of fscanf(in,%s,buf); */
pclose(in);

It seems that "popen" is the only way to get the actual return value(s). I use this method when I need to process a lot of data, but when I know it's just a one line return value from a unix cmd (e.g. - pwd, date, some grep cmd etc.), it's just seems overkill to have to use popen and the FILE pointers.

 

[xwb]

popen is the best way. Some of the others you've mentioned eg date, have C equivalents so you don't need to use the Unix commands.

 

[Salem]

getcwd is the API equivalent of the pwd command.



--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.

 

[cptk]

Yes, I know a few of my examples wouldn't actual require the popen method (e.g. date, pwd).

I was just trying to quickly illustrate some unix cmds that return singular results.

So I'm gathering it's true that there's no other means then to use a popen?

 

[Salem]

Well the other possible ways are even more long winded.

1. There's always roll your own using fork/exec/wait to organise the processes, open/close/dup to organise the file descriptors and read/write to get the information.

2. Or a poor substitute is to use system() to run the command to redirect to a file, then use regular fopen() to read the temp file. But then there's the removing the file when you're done.

> but when I know it's just a one line return value from a unix cmd (e.g. - pwd, date, some grep cmd etc.),
> it's just seems overkill to have to use popen and the FILE pointers.
So write your own function which runs a command and returns a single line, if that is the kind of thing you need to do a lot.


--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.

 

[cptk]

Salem -

If you mean write a general function that takes as an argument the char cmd to run in popen, that's what I already did.

Thanks ...