3 Standardised header
source | link

C, Linux (186 charsLinux), 186 bytes

#include<sys/ioctl.h>
#include<fcntl.h>
#include<stdio.h>
main(){char*s="Hello, World!",d[99],*c;fscanf(popen("tty","r"),"%s",d);int D=open(d,O_RDWR);for(c=s;*c;c++)ioctl(D,TIOCSTI,c);}

After applying ugoren's suggestions:

(111 chars)

111 bytes

main(D){char*c,d[99];fscanf(popen("tty","r"),"%s",d);D=open(d,2);for(c="Hello, World!";*c;)ioctl(D,21522,c++);}

C, Linux (186 chars)

#include<sys/ioctl.h>
#include<fcntl.h>
#include<stdio.h>
main(){char*s="Hello, World!",d[99],*c;fscanf(popen("tty","r"),"%s",d);int D=open(d,O_RDWR);for(c=s;*c;c++)ioctl(D,TIOCSTI,c);}

After applying ugoren's suggestions:

(111 chars)

main(D){char*c,d[99];fscanf(popen("tty","r"),"%s",d);D=open(d,2);for(c="Hello, World!";*c;)ioctl(D,21522,c++);}

C (Linux), 186 bytes

#include<sys/ioctl.h>
#include<fcntl.h>
#include<stdio.h>
main(){char*s="Hello, World!",d[99],*c;fscanf(popen("tty","r"),"%s",d);int D=open(d,O_RDWR);for(c=s;*c;c++)ioctl(D,TIOCSTI,c);}

After applying ugoren's suggestions:

111 bytes

main(D){char*c,d[99];fscanf(popen("tty","r"),"%s",d);D=open(d,2);for(c="Hello, World!";*c;)ioctl(D,21522,c++);}
2 shortening the code
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C, Linux (186 chars)

#include<sys/ioctl.h>
#include<fcntl.h>
#include<stdio.h>
main(){char*s="Hello, World!",d[99],*c;fscanf(popen("tty","r"),"%s",d);int D=open(d,O_RDWR);for(c=s;*c;c++)ioctl(D,TIOCSTI,c);}

After applying ugoren's suggestions:

(111 chars)

main(D){char*c,d[99];fscanf(popen("tty","r"),"%s",d);D=open(d,2);for(c="Hello, World!";*c;)ioctl(D,21522,c++);}

C, Linux (186 chars)

#include<sys/ioctl.h>
#include<fcntl.h>
#include<stdio.h>
main(){char*s="Hello, World!",d[99],*c;fscanf(popen("tty","r"),"%s",d);int D=open(d,O_RDWR);for(c=s;*c;c++)ioctl(D,TIOCSTI,c);}

C, Linux (186 chars)

#include<sys/ioctl.h>
#include<fcntl.h>
#include<stdio.h>
main(){char*s="Hello, World!",d[99],*c;fscanf(popen("tty","r"),"%s",d);int D=open(d,O_RDWR);for(c=s;*c;c++)ioctl(D,TIOCSTI,c);}

After applying ugoren's suggestions:

(111 chars)

main(D){char*c,d[99];fscanf(popen("tty","r"),"%s",d);D=open(d,2);for(c="Hello, World!";*c;)ioctl(D,21522,c++);}
1
source | link

C, Linux (186 chars)

#include<sys/ioctl.h>
#include<fcntl.h>
#include<stdio.h>
main(){char*s="Hello, World!",d[99],*c;fscanf(popen("tty","r"),"%s",d);int D=open(d,O_RDWR);for(c=s;*c;c++)ioctl(D,TIOCSTI,c);}