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support for head -n (suggested by xorquewasp)

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This commit is contained in:
David van Moolenbroek 2009-10-10 22:36:46 +00:00
parent fc2634d1ed
commit 0143cb2335
2 changed files with 20 additions and 9 deletions
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22
commands/simple/head.c
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@ -16,15 +16,25 @@ int argc;
char *argv[];
{
FILE *f;
int n, k, nfiles;
int legacy, n, k, nfiles;
char *ptr;
/* Check for flag. Only flag is -n, to say how many lines to print. */
/* Check for flags. One can only specify how many lines to print. */
k = 1;
ptr = argv[1];
n = DEFAULT;
if (argc > 1 && *ptr++ == '-') {
k++;
legacy = 0;
for (k = 1; k < argc && argv[k][0] == '-'; k++) {
ptr = &argv[k][1];
if (ptr[0] == 'n' && ptr[1] == 0) {
k++;
if (k >= argc) usage();
ptr = argv[k];
}
else if (ptr[0] == '-' && ptr[1] == 0) {
k++;
break;
}
else if (++legacy > 1) usage();
n = atoi(ptr);
if (n <= 0) usage();
}
@ -73,6 +83,6 @@ FILE *f;
void usage()
{
fprintf(stderr, "Usage: head [-n] [file ...]\n");
fprintf(stderr, "Usage: head [-lines | -n lines] [file ...]\n");
exit(1);
}

7
man/man1/head.1
View file

@ -2,7 +2,7 @@
.SH NAME
head \- print the first few lines of a file
.SH SYNOPSIS
\fBhead\fR [\fB\-\fIn\fR]\fR [\fIfile\fR] ...\fR
\fBhead\fR [\fB\-\fIn\fR | \fB\-n\fR \fIn\fR]\fR [\fIfile\fR] ...\fR
.br
.de FL
.TP
@ -15,9 +15,10 @@ head \- print the first few lines of a file
# \\$2
..
.SH OPTIONS
.FL "\-\fIn\fR" "How many lines to print"
.FL "\-n \fIn\fR" "How many lines to print"
.FL "\-\fIn\fR" "How many lines to print (backwards-compatible)"
.SH EXAMPLES
.EX "head \-6" "Print first 6 lines of \fIstdin\fR"
.EX "head \-n 6" "Print first 6 lines of \fIstdin\fR"
.EX "head \-1 file1 file2" "Print first line of two files"
.SH DESCRIPTION
.PP