2.9BSD/usr/man/man1/rev.1

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.TH REV 1 
.SH NAME
rev \- reverse lines of a file
.SH SYNOPSIS
.B rev
[ file ] ...
.SH DESCRIPTION
.I Rev
copies the named files to the standard output,
reversing the order of characters in every line.
If no file is specified, the standard input is copied.
.SH SEE ALSO
tail(1)