how to include command line in c program?

[kits]

i'm using RHEL.i'm new to linux and shell scripting.
i got this command that shows cpu usage :
"ps ux | awk '/process_name/ && !awk/ { print $2}"

1)can someone explain me what each thing signifies?

i know ps-process stat
awk-Find and Replace text


2)also..i;ve to write a c code.
how do i include this line in c so that it is executable in linux?

3)for example: i have to read a file from /proc/stat
how can i do that in c program?
in shell it is 'cat'...
like to print the file stat from /proc
whats the code for that?



thanks in advance

[Lakshmipathi]

i
2)also..i;ve to write a c code.
how do i include this line in c so that it is executable in linux?

i'm not sure about 1 and 3,
to write a command line program..it's very easy ...

hi.c
-----
main(int argc,char [] argv){
//some initial variables
if(argv[1] == 'a'){
//call some function
}
else if(argv[2] == 'b'){
//call some function-2
}
}

---------
gcc hi.c
./a.out a b
that' s it








}

[rajkumarmadhani]

for 3.
may be you can use like this

system("cat </proc/stat");

i'm using RHEL.i'm new to linux and shell scripting.
i got this command that shows cpu usage :
"ps ux | awk '/process_name/ && !awk/ { print $2}"

1)can someone explain me what each thing signifies?

i know ps-process stat
awk-Find and Replace text


2)also..i;ve to write a c code.
how do i include this line in c so that it is executable in linux?

3)for example: i have to read a file from /proc/stat
how can i do that in c program?
in shell it is 'cat'...
like to print the file stat from /proc
whats the code for that?



thanks in advance

[Cabhan]

Reading a file in C is a very simple task: if you don't know how, I'd recommend studying up some more on C before trying to write anything.

If you want to just print a file to stdout:

int c;
FILE *file;

file = fopen("file", "r");
while((c = getc(file)) != EOF)
    putchar(c);
fclose(file);

getc(FILE *) returns the next character (or the special symbol EOF if at the end of file). putchar(char) prints a character to stdout.

[rajkumarmadhani]

iam sorry cabhan,
reading from a file easy thing as you said.
But i thought mr kits asking the same(shell) in c.

Reading a file in C is a very simple task: if you don't know how, I'd recommend studying up some more on C before trying to write anything.

If you want to just print a file to stdout:

int c;
FILE *file;

file = fopen("file", "r");
while((c = getc(file)) != EOF)
    putchar(c);
fclose(file);

getc(FILE *) returns the next character (or the special symbol EOF if at the end of file). putchar(char) prints a character to stdout.

[Cabhan]

I actually was referring to kits, not you. Though with cat, since it takes in a filename, you don't need to do "cat < /proc/stat". You can just say "cat /proc/stat".

My message to kits is just that if you're going to try writing a full program in C, it would likely be useful to know how to do I/O first...