dcn@ihuxl.UUCP (Dave Newkirk) (11/14/83)
/* tail - print last part of file */
#include "stdio.h"
int lines, chars ;
main(argc, argv)
int argc ;
char *argv[] ;
{
char *s ;
FILE *input ;
int count ;
argc-- ; argv++ ;
lines = TRUE ;
chars = FALSE ;
count = -10 ;
if( argc == 0 ) {
tail( stdin, count ) ;
exit(0) ;
}
s = *argv ;
if( *s == '-' || *s == '+' ) {
s++ ;
if( *s >= '0' && *s <= '9' ) {
count = stoi( *argv ) ;
s++ ;
while( *s >= '0' && *s <= '9' )
s++ ;
}
if( *s == 'c' ) {
chars = TRUE ;
lines = FALSE ;
}
else if( *s != 'l' && *s != EOS ) {
fprintf(stderr, "tail: unknown option %c\n", *s ) ;
argc = 0 ;
}
argc-- ; argv++ ;
}
if( argc < 0 ) {
fprintf(stderr, "usage: tail [+/-[number][lc]] [files]\n");
exit(1) ;
}
if( argc == 0 )
tail( stdin, count ) ;
else if( (input=fopen(*argv,"r")) == NULL ) {
fprintf(stderr, "tail: can't open %s\n", *argv) ;
exit(1) ;
}
else {
tail( input, count ) ;
fclose( input ) ;
}
exit(0) ;
} /* end main */
/* stoi - convert string to integer */
stoi(s)
char *s ;
{
int n, sign ;
while( *s == BLANK || *s == NL || *s == TAB )
s++ ;
sign = 1 ;
if( *s == '+' )
s++ ;
else if( *s == '-' ) {
sign = -1 ;
s++ ;
}
for( n=0 ; *s >= '0' && *s <= '9' ; s++ )
n = 10 * n + *s - '0' ;
return( sign * n ) ;
}
/* tail - print 'count' lines/chars */
#define INCR(p) if(p >= end) p=cbuf ; else p++
#define BUFSIZE 4098
char cbuf[ BUFSIZE ] ;
tail( in, goal )
FILE *in ;
int goal ;
{
int c, count ;
char *start, *finish, *end ;
count = 0 ;
if( goal > 0 ) { /* skip */
if( lines ) /* lines */
while( (c=agetc(in)) != EOF ) {
if( c == NL )
count++ ;
if( count >= goal )
break ;
}
else /* chars */
while( agetc(in) != EOF ) {
count++ ;
if( count >= goal )
break ;
}
if( count >= goal )
while( (c=agetc(in)) != EOF )
aputc(c, stdout ) ;
}
else { /* tail */
goal = -goal ;
start = finish = cbuf ;
end = &cbuf[ BUFSIZE - 1 ] ;
while( (c=agetc(in)) != EOF ) {
*finish = c ;
INCR( finish ) ;
if( start == finish )
INCR( start ) ;
if( !lines || c == NL )
count++ ;
if( count > goal ) {
count = goal ;
if( lines )
while( *start != NL )
INCR( start ) ;
INCR( start ) ;
}
} /* end while */
while( start != finish ) {
aputc( *start, stdout ) ;
INCR( start ) ;
}
} /* end else */
} /* end tail */