4.3BSD/usr/contrib/tac/tac.1

.\"	@(#)tac.1	1.2 6/5/86
.\"
.TH TAC 1 "June 5, 1986"
.SH NAME
tac \- concatenate and print files in reverse
.SH SYNOPSIS
.B tac
[
.B \-string
] [
.B +string
] [ file ... ]
.SH DESCRIPTION
.I Tac
reads each
.I file
in sequence
and writes it on the standard output, reversed by the file segments
delimited by
.I string.
.I \-string
specifies segments bounded on the left by
.I string,
while
.I +string
specifies right-bounded segments.
The default is
.I +\en
(print lines in reverse order).
If no input
.I file
is given, or if the argument `-'
is encountered,
.I tac
reads from the standard input.  Note that in this case
.I tac
stores the entire standard input in a temporary
file before it outputs anything, so for large input it is slow.
.SH EXAMPLES
.RS
tac '-\e
.br
From\ ' /usr/spool/mail/$USER
.RE
prints out one's mail messages, most recent first.
.PP
.RS
tac file
.RE
prints the file in reverse, line by line, and:
.PP
.RS
tac /usr/adm/messages | egrep 'hp.*hard'
.RE
prints out the hard errors on MASSBUS disk drives, most recent first.
.SH SEE ALSO
cat(1), rev(1), tail(1), tmail(1)
.SH BUGS
.I Tac
doesn't handle multiple argument files exactly right, and it's
also unclear in which order they should be processed.
.br
If invoked as `tac < file', 
.I tac
uses a temp file but it doesn't have to.