w64devkit/man/man1/uuencode.1

.TH UUENCODE 1 2026-10-19 "w64devkit" "w64devkit Manual"
.SH NAME
uuencode \- encode a file as text in uuencode or base64 form
.SH SYNOPSIS
.B uuencode
.RB [ \-m ]
.RI [ file ]
.I name
.SH DESCRIPTION
.B uuencode
writes
.I file
to standard output as printable ASCII text that
.BR uudecode (1)
turns back into the same bytes.
With two operands, it reads
.I file
and stores
.IR name .
With one operand, it reads standard input, and the operand is
.IR name .
.PP
.I name
is copied into the first line of the output.
It is the name that
.BR uudecode (1)
gives the decoded file unless told otherwise.
It is written exactly as given, so a directory part or a backslash
stays.
.PP
The input is read in full 45-byte pieces, so every data line but the
last encodes 45 bytes, however the input arrives.
Lines end with LF.
.SS Output format
The output has a header line, data lines, and a trailer.
The header is a keyword, the mode in octal, and
.IR name ,
separated by single spaces; see
.BR Mode .
Empty input has no data lines.
.PP
By default the keyword is
.BR begin .
A data line is a length character and then 4 characters for each 3
input bytes, rounded up, with the last group completed by zero bits.
The length character is the number of input bytes on the line plus 32,
so a full line starts with
.BR M .
Every other character is a 6-bit value plus 32, except that 0 is
written as a grave accent
.RB ( \(ga )
and not a space, so the characters run from
.B !\&
to
.BR \(ga .
The trailer is a line holding only a grave accent, which is the length
0, and then a line holding
.BR end .
.PP
With
.BR \-m ,
the keyword is
.BR begin\-base64 .
A data line has no length character.
It is 60 characters of base64 for 45 bytes, using the alphabet
.B A
to
.BR Z ,
.B a
to
.BR z ,
.B 0
to
.BR 9 ,
.BR + ,
and
.BR / .
The last line is padded with
.B =
to a multiple of 4 characters.
The trailer is a line holding
.BR ==== .
.SS Mode
Windows files have no Unix permissions, so the mode in the header is
made up:
.IP \(bu 2
For a named
.IR file ,
it is 644, or 444 if the file is read-only.
No execute bits are ever set, even for an
.I .exe
file.
The file mode creation mask has no effect.
.IP \(bu 2
For standard input, it is 666 without the bits of the file mode
creation mask.
The mask is 002 unless
.B BB_UMASK
says otherwise, so the mode is 664 by default.
The file that standard input comes from is not examined.
.SH OPTIONS
Options may follow the operands, unless
.B POSIXLY_CORRECT
is set.
.B \-\-
ends the options.
.TP
.B \-m
Write base64 instead of the uuencode format, as described in
.BR "Output format" .
.TP
.B \-\-help
As the first argument, print a usage message on standard output and
exit.
.SH ENVIRONMENT
.TP
.B BB_UMASK
The file mode creation mask, in octal, used for the mode of standard
input.
The default is
.BR 002 .
The
.B umask
command of
.BR sh (1)
sets and exports it.
.TP
.B POSIXLY_CORRECT
If set, options must precede the operands.
Then
.B uuencode a \-m
encodes the file
.I a
under the name
.BR \-m ,
where otherwise it encodes standard input as base64 under the name
.IR a .
.PP
Variables that busybox-w32 reads in every applet, such as those that
control console output, are described in
.BR busybox (1).
.SH EXIT STATUS
.TP
.B 0
Success.
.TP
.B 1
No operands, more than two operands, an unknown option, a
.I file
that cannot be opened or read, or an error writing standard output.
A usage error prints the usage on standard error.
.TP
.B 141
Standard output is a pipe whose reader has exited.
.PP
A file that cannot be opened is reported on standard error as
.PP
.RS 4
.EX
uuencode: can\(aqt open \(aq\fIfile\fR\(aq: \fIreason\fR
.EE
.RE
.PP
Output written before an error stays written, so a failure in the
middle of the input leaves text with no trailer.
.SH EXAMPLES
Encode a file under its own name:
.PP
.RS 4
.EX
$ uuencode hello.txt hello.txt
begin 644 hello.txt
\&.2&5L;&\eL(\(aq=O<FQD(0H\(ga
\(ga
end
.EE
.RE
.PP
Encode as base64 instead:
.PP
.RS 4
.EX
$ uuencode \-m hello.txt hello.txt
begin\-base64 644 hello.txt
SGVsbG8sIHdvcmxkIQo=
====
.EE
.RE
.PP
Encode the output of another command under the name
.IR dump.bin :
.PP
.RS 4
.EX
$ head \-c 1024 /dev/urandom | uuencode dump.bin >dump.uu
.EE
.RE
.PP
Store only the file name, not the directory part:
.PP
.RS 4
.EX
$ uuencode build/app.exe app.exe >app.uu
.EE
.RE
.PP
Decode it, creating
.IR app.exe :
.PP
.RS 4
.EX
$ uudecode app.uu
.EE
.RE
.SH NOTES
There are no long options other than
.BR \-\-help ,
so GNU's
.B \-\-base64
is an unknown option.
.PP
A
.I file
named
.B \-
is not standard input, and fails to open unless a file of that name
exists.
To read standard input, give one operand.
Giving
.I /dev/stdin
as
.I file
also reads standard input, but its mode follows the rule for a named
.IR file .
.PP
The input is read in binary mode and the output has LF line endings, so
a round trip through
.BR uudecode (1)
reproduces the bytes exactly.
.PP
.I file
may be a Windows path, with a drive letter and either kind of slash, or
a busybox-w32 device name such as
.IR /dev/null .
A directory fails to open with
.BR "Permission denied" .
There is no limit on the size of the input.
.SH SEE ALSO
.BR base32 (1),
.BR base64 (1),
.BR busybox (1),
.BR sh (1),
.BR uudecode (1)