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UUENCODE(1) NetBSD General Commands Manual UUENCODE(1)
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uuencode, uudecode -- encode/decode a binary file
uuencode [-m] [inputfile] headername
uudecode [-m] [-p | -o outputfile] [encoded-file ...]
uuencode and uudecode are used to transmit binary files over transmission
mediums that do not support other than simple ASCII data.
The following options are available:
-m Use base64 encoding. For uuencode, the historical uuencode algorithm
is the default. For uudecode, by default the encoding is automati-
(uudecode only.) Send the decoded output data to outputfile. By
default, uudecode uses the headername recorded in the header of the
encoded data stream.
-p (uudecode only.) Write the decoded file to standard output instead
of to a file.
uuencode reads inputfile (or by default the standard input) and writes an
encoded version to (always) the standard output. The encoding uses only
printing ASCII characters suitable for text-only transport media. The
string headername is inserted into the output header as the outputfile to
use at uudecode time. The header also includes the mode (permissions) of
uudecode transforms uuencoded files (or by default, the standard input)
into the original form. The resulting file is named headername as
recorded in the encoded file, or as specified by the -o option, and will
have the mode of the original file except that setuid and execute bits
are not retained. If the -p option is specified, or if the output file
name is given as /dev/stdout, then the data will be written to the stan-
dard output instead of to a named file. uudecode ignores any leading and
The encoded form of the file is expanded by 35%. Every 3 bytes become 4
plus control information.
The uudecode and uuencode utilities exits 0 on success, and >0 if an
The following example packages up a source tree, compresses it, uuencodes
it and mails it to a user on another system.
tar czf - src_tree | uuencode src_tree.tgz | mail firstname.lastname@example.org
On the other system, if the user saves the mail to the file temp, the
following example creates the file src_tree.tgz and extracts it to make a
copy of the original tree.
tar xzf src_tree.tgz
gzip(1), mail(1), tar(1), uuencode(5)
The uudecode and uuencode utilities conform to IEEE Std 1003.1-2008
The uudecode and uuencode utilities appeared in 4.0BSD.
When using uudecode with files coming from dubious sources, always either
explicitly pass the -o option or check the header (the first line) of the
encoded file for safety. Blindly using a headername from a hostile
source can overwrite important files.
NetBSD 9.2 September 6, 2014 NetBSD 9.2