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.\"     @(#)uuencode.1	8.1 (Berkeley) 6/6/93
.\"
.Dd September 6, 2014
.Dt UUENCODE 1
.Os
.Sh NAME
.Nm uuencode ,
.Nm uudecode
.Nd encode/decode a binary file
.Sh SYNOPSIS
.Nm
.Op Fl m
.Op Ar inputfile
.Ar headername
.Nm uudecode
.Op Fl m
.Op Fl p | Fl o Ar outputfile
.Op Ar encoded-file ...
.Sh DESCRIPTION
.Nm
and
.Nm uudecode
are used to transmit binary files over transmission mediums
that do not support other than simple
.Tn ASCII
data.
.Pp
The following options are available:
.Bl -tag -width ".Fl m"
.It Fl m
Use base64 encoding.
For
.Nm ,
the historical uuencode algorithm is the default.
For
.Nm uudecode ,
by default the encoding is automatically detected.
.It Fl o Ar outputfile
.Po Nm uudecode No only . Pc
Send the decoded output data to
.Ar outputfile .
By default,
.Nm uudecode
uses the
.Ar headername
recorded in the header of the encoded data stream.
.It Fl p
.Po Nm uudecode No only . Pc
Write the decoded file to standard output instead of to a file.
.El
.Pp
.Nm
reads
.Ar inputfile
(or by default the standard input) and writes an encoded version
to (always) the standard output.
The encoding uses only printing
.Tn ASCII
characters suitable for text-only transport media.
The string
.Ar headername
is inserted into the output header as the
.Ar outputfile
to use at
.Nm uudecode
time.
The header also includes the mode (permissions) of the file.
.Pp
.Nm uudecode
transforms
.Em uuencoded
files (or by default, the standard input) into the original form.
The resulting file is named
.Ar headername
as recorded in the encoded file,
or as specified by the
.Fl o
option,
and will have the mode of the original file except that setuid
and execute bits are not retained.
If the
.Fl p
option is specified, or if the output file name is given as
.Pa /dev/stdout ,
then the data will be written to the standard output
instead of to a named file.
.Nm uudecode
ignores any leading and trailing lines.
.Pp
The encoded form of the file is expanded by 35%.
Every 3 bytes become 4 plus control information.
.Sh EXIT STATUS
The
.Nm uudecode
and
.Nm
utilities exits 0 on success, and \*[Gt]0 if an error occurs.
.Sh EXAMPLES
The following example packages up a source tree, compresses it,
uuencodes it and mails it to a user on another system.
.Pp
.Bd -literal -offset indent -compact
tar czf \- src_tree \&| uuencode src_tree.tgz \&| mail user@example.com
.Ed
.Pp
On the other system, if the user saves the mail to the file
.Pa temp ,
the following example creates the file
.Pa src_tree.tgz
and extracts it to make a copy of the original tree.
.Pp
.Bd -literal -offset indent -compact
uudecode temp
tar xzf src_tree.tgz
.Ed
.Sh SEE ALSO
.Xr gzip 1 ,
.Xr mail 1 ,
.Xr tar 1 ,
.\".Xr uucp 1 ,
.Xr uuencode 5
.Sh STANDARDS
The
.Nm uudecode
and
.Nm
utilities conform to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Nm uudecode
and
.Nm
utilities appeared in
.Bx 4.0 .
.Sh SECURITY CONSIDERATIONS
When using
.Nm uudecode
with files coming from dubious sources,
always either explicitly pass the
.Fl o
option or check the header (the first line) of the encoded file for
safety.
Blindly using a
.Ar headername
from a hostile source can overwrite important files.