d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add -l option to cat(1). This option causes cat(1) to use fcntl(2) to

Browse Source 
set an exclusive advisory lock on stdout.  This will be used to guarantee
orderly writing to METALOG.

Sponsored by:	DARPA, AFRL
Obtained from:	NetBSD (mason)
This commit is contained in:
Brooks Davis 2013-01-29 18:19:40 +00:00
parent 2d0d4f6b5e
commit aece80a2e8
2 changed files with 30 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
bin/cat/cat.1
View File

@ -32,7 +32,7 @@
.\" @(#)cat.1 8.3 (Berkeley) 5/2/95
.\" $FreeBSD$
.\"
.Dd March 21, 2004
.Dd Jaunary 29, 2013
.Dt CAT 1
.Os
.Sh NAME
@ -40,7 +40,7 @@
.Nd concatenate and print files
.Sh SYNOPSIS
.Nm
.Op Fl benstuv
.Op Fl belnstuv
.Op Ar
.Sh DESCRIPTION
The
@ -79,6 +79,16 @@ Display non-printing characters (see the
option), and display a dollar sign
.Pq Ql \&$
at the end of each line.
.It Fl l
Set an exclusive advisory lock on the standard output file descriptor.
This lock is set using
.Xr fcntl 2
with the
.Dv F_SETLKW
command.
If the output file is already locked,
.Nm
will block until the lock is acquired.
.It Fl n
Number the output lines, starting at 1.
.It Fl s
@ -160,6 +170,7 @@ operand.
.Xr tail 1 ,
.Xr vis 1 ,
.Xr zcat 1 ,
.Xr fcntl 2 ,
.Xr setbuf 3
.Rs
.%A Rob Pike
@ -175,7 +186,7 @@ utility is compliant with the
specification.
.Pp
The flags
.Op Fl benstv
.Op Fl belnstv
are extensions to the specification.
.Sh HISTORY
A

19
bin/cat/cat.c
View File

@ -64,7 +64,7 @@ __FBSDID("$FreeBSD$");
#include <string.h>
#include <unistd.h>
static int bflag, eflag, nflag, sflag, tflag, vflag;
static int bflag, eflag, lflag, nflag, sflag, tflag, vflag;
static int rval;
static const char *filename;
@ -96,10 +96,11 @@ int
main(int argc, char *argv[])
{
int ch;
struct flock stdout_lock;
setlocale(LC_CTYPE, "");
while ((ch = getopt(argc, argv, "benstuv")) != -1)
while ((ch = getopt(argc, argv, "belnstuv")) != -1)
switch (ch) {
case 'b':
bflag = nflag = 1; /* -b implies -n */
@ -107,6 +108,9 @@ main(int argc, char *argv[])
case 'e':
eflag = vflag = 1; /* -e implies -v */
break;
case 'l':
lflag = 1;
break;
case 'n':
nflag = 1;
break;
@ -127,6 +131,15 @@ main(int argc, char *argv[])
}
argv += optind;
if (lflag) {
stdout_lock.l_len = 0;
stdout_lock.l_start = 0;
stdout_lock.l_type = F_WRLCK;
stdout_lock.l_whence = SEEK_SET;
if (fcntl(STDOUT_FILENO, F_SETLKW, &stdout_lock) == -1)
err(EXIT_FAILURE, "stdout");
}
if (bflag || eflag || nflag || sflag || tflag || vflag)
scanfiles(argv, 1);
else
@ -140,7 +153,7 @@ main(int argc, char *argv[])
static void
usage(void)
{
fprintf(stderr, "usage: cat [-benstuv] [file ...]\n");
fprintf(stderr, "usage: cat [-belnstuv] [file ...]\n");
exit(1);
/* NOTREACHED */
}