commit bf9626d408bc5c5fd3e538d02686327ddc525d6e
parent 0236550c77f528c3f05d6f0c6d721f01f6b39002
Author: Connor Lane Smith <cls@lubutu.com>
Date: Thu, 26 May 2011 16:18:42 -0100
add tail
Diffstat:
9 files changed, 130 insertions(+), 20 deletions(-)
diff --git a/Makefile b/Makefile
@@ -1,8 +1,10 @@
include config.mk
-LIB = util/afgets.o util/agetcwd.o util/enmasse.o util/eprintf.o util/recurse.o
+LIB = util/afgets.o util/agetcwd.o util/concat.o util/enmasse.o util/eprintf.o \
+ util/recurse.o
SRC = basename.c cat.c chown.c date.c dirname.c echo.c false.c grep.c head.c \
- ln.c ls.c mkdir.c mkfifo.c pwd.c rm.c sleep.c tee.c touch.c true.c wc.c
+ ln.c ls.c mkdir.c mkfifo.c pwd.c rm.c sleep.c tail.c tee.c touch.c \
+ true.c wc.c
OBJ = $(SRC:.c=.o) $(LIB)
BIN = $(SRC:.c=)
MAN = $(SRC:.c=.1)
diff --git a/basename.1 b/basename.1
@@ -13,4 +13,5 @@ with any leading path components, and the
.IR suffix ,
removed.
.SH SEE ALSO
+.IR dirname (1),
.IR basename (3)
diff --git a/cat.c b/cat.c
@@ -2,10 +2,9 @@
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
+#include "text.h"
#include "util.h"
-static void cat(FILE *, const char *);
-
int
main(int argc, char *argv[])
{
@@ -14,25 +13,12 @@ main(int argc, char *argv[])
if(getopt(argc, argv, "") != -1)
exit(EXIT_FAILURE);
if(optind == argc)
- cat(stdin, "<stdin>");
+ concat(stdin, "<stdin>", stdout, "<stdout>");
else for(; optind < argc; optind++) {
if(!(fp = fopen(argv[optind], "r")))
eprintf("fopen %s:", argv[optind]);
- cat(fp, argv[optind]);
+ concat(fp, argv[optind], stdout, "<stdout>");
fclose(fp);
}
return EXIT_SUCCESS;
}
-
-void
-cat(FILE *fp, const char *str)
-{
- char buf[BUFSIZ];
- size_t n;
-
- while((n = fread(buf, 1, sizeof buf, fp)) > 0)
- if(fwrite(buf, 1, n, stdout) != n)
- eprintf("<stdout>: write error:");
- if(ferror(fp))
- eprintf("%s: read error:", str);
-}
diff --git a/dirname.1 b/dirname.1
@@ -10,4 +10,5 @@ prints the
.I string
with its final path component removed.
.SH SEE ALSO
+.IR basename (1),
.IR dirname (3)
diff --git a/head.1 b/head.1
@@ -14,3 +14,5 @@ reads from stdin.
.TP
.BI \-n " lines"
outputs the given number of lines.
+.SH SEE ALSO
+.IR tail (1)
diff --git a/tail.1 b/tail.1
@@ -0,0 +1,20 @@
+.TH TAIL 1 sbase\-VERSION
+.SH NAME
+tail \- output last part of a file
+.SH SYNOPSIS
+.B tail
+.RB [ \-n
+.IR lines ]
+.RI [ file ]
+.SH DESCRIPTION
+.B tail
+writes the first 10 lines of the file to stdout. If no file is given, tail
+reads from stdin.
+.SH OPTIONS
+.TP
+.BI \-n " lines"
+outputs the given number of lines. If
+.I lines
+begins with '+' it is used as an offset from the beginning of the file.
+.SH SEE ALSO
+.IR head (1)
diff --git a/tail.c b/tail.c
@@ -0,0 +1,80 @@
+/* See LICENSE file for copyright and license detaketails. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "text.h"
+#include "util.h"
+
+static void dropinit(FILE *, const char *, long);
+static void taketail(FILE *, const char *, long);
+
+static void (*tail)(FILE *, const char *, long) = taketail;
+
+int
+main(int argc, char *argv[])
+{
+ char *end, c;
+ long n = 10;
+ FILE *fp;
+
+ while((c = getopt(argc, argv, "n:")) != -1)
+ switch(c) {
+ case 'n':
+ n = abs(strtol(optarg, &end, 0));
+ if(*end != '\0')
+ eprintf("%s: not a number\n", optarg);
+ if(optarg[0] == '+')
+ tail = dropinit;
+ break;
+ default:
+ exit(EXIT_FAILURE);
+ }
+ if(optind == argc)
+ tail(stdin, "<stdin>", n);
+ else if(optind == argc-1) {
+ if(!(fp = fopen(argv[optind], "r")))
+ eprintf("fopen %s:", argv[optind]);
+ tail(fp, argv[optind], n);
+ fclose(fp);
+ }
+ else
+ eprintf("usage: %s [-n lines] [file]\n", argv[0]);
+
+ return EXIT_SUCCESS;
+}
+
+void
+dropinit(FILE *fp, const char *str, long n)
+{
+ char buf[BUFSIZ];
+ long i = 0;
+
+ while(i < n && fgets(buf, sizeof buf, fp))
+ if(buf[strlen(buf)-1] == '\n')
+ i++;
+ concat(fp, str, stdout, "<stdout>");
+}
+
+void
+taketail(FILE *fp, const char *str, long n)
+{
+ char **ring;
+ long i, j;
+ size_t *size;
+
+ if(!(ring = calloc(n, sizeof *ring)) || !(size = calloc(n, sizeof *size)))
+ eprintf("calloc:");
+ for(i = j = 0; afgets(&ring[i], &size[i], fp); i = j = (i+1)%n)
+ ;
+
+ do {
+ if(ring[j])
+ fputs(ring[j], stdout);
+ } while((j = (j+1)%n) != i);
+ free(ring);
+ free(size);
+
+ if(ferror(fp))
+ eprintf("%s: read error:", str);
+}
diff --git a/text.h b/text.h
@@ -1,3 +1,4 @@
/* See LICENSE file for copyright and license details. */
-char *afgets(char **p, size_t *size, FILE *fp);
+char *afgets(char **, size_t *, FILE *);
+void concat(FILE *, const char *, FILE *, const char *);
diff --git a/util/concat.c b/util/concat.c
@@ -0,0 +1,17 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include "../text.h"
+#include "../util.h"
+
+void
+concat(FILE *fp1, const char *s1, FILE *fp2, const char *s2)
+{
+ char buf[BUFSIZ];
+ size_t n;
+
+ while((n = fread(buf, 1, sizeof buf, fp1)) > 0)
+ if(fwrite(buf, 1, n, fp2) != n)
+ eprintf("%s: write error:", s2);
+ if(ferror(fp1))
+ eprintf("%s: read error:", s1);
+}
