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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[]; char *argv[];
{ {
FILE *f; FILE *f;
int n, k, nfiles; int legacy, n, k, nfiles;
char *ptr; 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; k = 1;
ptr = argv[1];
n = DEFAULT; n = DEFAULT;
if (argc > 1 && *ptr++ == '-') { legacy = 0;
k++; 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); n = atoi(ptr);
if (n <= 0) usage(); if (n <= 0) usage();
} }
@ -73,6 +83,6 @@ FILE *f;
void usage() void usage()
{ {
fprintf(stderr, "Usage: head [-n] [file ...]\n"); fprintf(stderr, "Usage: head [-lines | -n lines] [file ...]\n");
exit(1); exit(1);
} }

7
man/man1/head.1
View file

@ -2,7 +2,7 @@
.SH NAME .SH NAME
head \- print the first few lines of a file head \- print the first few lines of a file
.SH SYNOPSIS .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 .br
.de FL .de FL
.TP .TP
@ -15,9 +15,10 @@ head \- print the first few lines of a file
# \\$2 # \\$2
.. ..
.SH OPTIONS .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 .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" .EX "head \-1 file1 file2" "Print first line of two files"
.SH DESCRIPTION .SH DESCRIPTION
.PP .PP