sbase/head.c

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C
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/* See LICENSE file for copyright and license details. */
#include <errno.h>
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#include <stdio.h>
#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
#include "util.h"
static void head(FILE *, const char *, long);
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static void
usage(void)
{
eprintf("usage: %s [-n] [FILE...]\n", argv0);
}
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int
main(int argc, char *argv[])
{
long n = 10;
FILE *fp;
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ARGBEGIN {
case 'n':
n = estrtol(EARGF(usage()), 0);
break;
ARGNUM:
n = ARGNUMF(0);
break;
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default:
usage();
} ARGEND;
if(argc == 0) {
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head(stdin, "<stdin>", n);
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} else for(; argc > 0; argc--, argv++) {
if(!(fp = fopen(argv[0], "r"))) {
fprintf(stderr, "fopen %s: %s\n", argv[0],
strerror(errno));
continue;
}
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head(fp, argv[0], n);
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fclose(fp);
}
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return EXIT_SUCCESS;
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}
void
head(FILE *fp, const char *str, long n)
{
char buf[BUFSIZ];
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long i = 0;
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while(i < n && fgets(buf, sizeof buf, fp)) {
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fputs(buf, stdout);
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if(buf[strlen(buf)-1] == '\n')
i++;
}
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if(ferror(fp))
eprintf("%s: read error:", str);
}