1uuencode(1C) Communication Commands uuencode(1C)
2
6 uuencode, uudecode - encode a binary file, or decode its encoded repre‐
7 sentation
8
10 uuencode [source-file] decode_pathname
11 uuencode [-m] [source-file] decode_pathname
14 uudecode [-p] [encoded-file]
17 uudecode [-o outfile] [encoded-file]
20
23 These commands encode and decode files as follows:
24 uuencode
26 The uuencode utility converts a binary file into an encoded representa‐
27 tion that can be sent using mail(1). It encodes the contents of source-
28 file, or the standard input if no source-file argument is given. The
29 decode_pathname argument is required. The decode_pathname is included
30 in the encoded file's header as the name of the file into which uude‐
31 code is to place the binary (decoded) data. uuencode also includes the
32 permission modes of source-file (except setuid, setgid, and sticky-
33 bits), so that decode_pathname is recreated with those same permission
34 modes.
35 uudecode
37 The uudecode utility reads an encoded-file, strips off any leading and
38 trailing lines added by mailer programs, and recreates the original
39 binary data with the filename and the mode specified in the header.
40 The encoded file is an ordinary portable character set text file; it
43 can be edited by any text editor. It is best only to change the mode or
44 decode_pathname in the header to avoid corrupting the decoded binary.
45
47 The following options are supported:
48 uuencode
50 -m Encodes source-file using Base64 encoding and sends it to stan‐
51 dard output.
52 uudecode
55 -o outfile Specifies a file pathname that should be used instead of
56 any pathname contained in the input data. Specifying an
57 outfile option-argument of /dev/stdout indicates standard
58 output.This allows uudecode to be used in a pipeline.
59 -p Decodes encoded-file and sends it to standard output.
62 This allows uudecode to be used in a pipeline.
63
66 The following operands are supported by uuencode and uudecode:
67 uuencode
69 decode_pathname The pathname of the file into which the uudecode
70 utility will place the decoded file. If there are
71 characters in decode_pathname that are not in the
72 portable filename character set, the results are
73 unspecified.
74 source-file A pathname of the file to be encoded.
77 uudecode
80 encoded-file The pathname of a file containing the output of uuen‐
81 code.
82
85 See largefile(5) for the description of the behavior of uuencode and
86 uudecode when encountering files greater than or equal to 2 Gbyte (
87 2^31 bytes).
88
90 See environ(5) for descriptions of the following environment variables
91 that affect the execution of uuencode and uudecode: LANG, LC_ALL,
92 LC_CTYPE, LC_MESSAGES, and NLSPATH.
93
95 stdout
96 uuencode Base64 Algorithm
98 The standard output is a text file, encoded in the character set of the
99 current locale, that begins with the line:
100 begin-base64 %s %s0 mode, decode_pathname
102 and ends with the line:
107 ====
109 In both cases, the lines have no preceding or trailing blank charac‐
114 ters.
115 The encoding process represents 24-bit groups of input bits as output
118 strings of four encoded characters. Proceeding from left to right, a
119 24-bit input group is formed by concatenating three 8-bit input groups.
120 Each 24-bit input group is then treated as four concatenated 6-bit
121 groups, each of which is translated into a single digit in the Base64
122 alphabet. When encoding a bit stream by means of the Base64 encoding,
123 the bit stream is presumed to be ordered with the most-significant bit
124 first. That is, the first bit in the stream is the high-order bit in
125 the first byte, and the eighth bit is the low-order bit in the first
126 byte, and so on. Each 6-bit group is used as an index into an array of
127 64 printable characters, as shown in the following table.
128 Value Encoding Value Encoding Value Encoding Value Encoding
130 0 A 17 R 34 i 51 z
131 1 B 18 S 35 j 52 0
132 2 C 19 T 36 k 53 1
133 3 D 20 U 37 l 54 2
134 4 E 21 V 38 m 55 3
135 5 F 22 W 39 n 56 4
136 6 G 23 X 40 o 57 5
137 7 H 24 Y 41 p 58 6
138 8 I 25 Z 42 q 59 7
139 9 J 26 a 43 r 60 8
140 10 K 27 b 44 s 61 9
141 11 L 28 c 45 t 62 +
142 12 M 29 d 46 u 63 /
143 13 N 30 e 47 v
144 14 O 31 f 48 w (pad) =
145 15 P 32 g 49 x
146 16 Q 33 h 50 y
147 The character referenced by the index is placed in the output string.
152 The output stream (encoded bytes) is represented in lines of no more
155 than 76 characters each. All line breaks or other characters not found
156 in the table are ignored by decoding software (see uudecode).
157 Special processing is performed if fewer than 24 bits are available at
160 the end of a message or encapsulated part of a message. A full encoding
161 quantum is always completed at the end of a message. When fewer than 24
162 input bits are available in an input group, zero bits are added on the
163 right to form an integral number of 6-bit groups. Output character
164 positions that are not required to represent actual input data are set
165 to the equals (=) character. Since all Base64 input is an integral num‐
166 ber of octets, only the following cases can arise:
167 1. The final quantum of encoding input is an integral multiple
169 of 24 bits. Here, the final unit of encoded output is an
170 integral multiple of four characters with no '= ' padding.
171 2. The final quantum of encoding input is exactly 16 bits.
173 Here, the final unit of encoded output is three characters
174 followed by one '=' padding character.
175 3. The final quantum of encoding input is exactly 8 bits. Here,
177 the final unit of encoded output is two characters followed
178 by two '=' padding characters.
179 A terminating "====" evaluates to nothing and denotes the end of the
182 encoded data.
183 uuencode Historical Algorithm
185 The standard output is a text file (encoded in the character set of the
186 current locale) that begins with the line:
187 begin %s %s\n, mode, decode_pathname
189 and ends with the line:
194 end\n
196 In both cases, the lines have no preceding or trailing blank charac‐
201 ters.
202 The algorithm that is used for lines between begin and end takes three
205 octets as input and writes four characters of output by splitting the
206 input at six-bit intervals into four octets, containing data in the
207 lower six bits only. These octets are converted to characters by adding
208 a value of 0x20 to each octet, so that each octet is in the range
209 0x20−0x5f, and each octet is assumed to represent a printable charac‐
210 ter. Each octect is then translated into the corresponding character
211 codes for the codeset in use in the current locale. For example, the
212 octet 0x41, representing 'A', would be translated to 'A' in the current
213 codeset, such as 0xc1 if the codeset were EBCDIC.
214 Where the bits of two octets are combined, the least significant bits
217 of the first octet are shifted left and combined with the most signifi‐
218 cant bits of the second octet shifted right. Thus, the three octets A,
219 B, C are converted into the four octets:
220 0x20 + (( A >> 2 ) & 0x3F)
222 0x20 + (((A << 4) ((B >> 4) & 0xF)) & 0x3F)
223 0x20 + (((B << 2) ((C >> 6) & 0x3)) & 0x3F)
224 0x20 + (( C ) & 0x3F)
225 These octets are then translated into the local character set.
230 Each encoded line contains a length character, equal to the number of
233 characters to be decoded plus 0x20 translated to the local character
234 set as described above, followed by the encoded characters. The maximum
235 number of octets to be encoded on each line is 45.
236
238 The following exit values are returned:
239 0 Successful completion.
241 >0 An error occurred.
244
247 See attributes(5) for descriptions of the following attributes:
248 ┌─────────────────────────────┬─────────────────────────────┐
253 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
254 ├─────────────────────────────┼─────────────────────────────┤
255 │Availability │SUNWesu │
256 ├─────────────────────────────┼─────────────────────────────┤
257 │Interface Stability │Standard │
258 └─────────────────────────────┴─────────────────────────────┘
259
261 mail(1), mailx(1), uucp(1C), uux(1C), attributes(5), environ(5), large‐
262 file(5), standards(5)
263
265 The size of the encoded file is expanded by 35% (3 bytes become 4, plus
266 control information), causing it to take longer to transmit than the
267 equivalent binary.
268 The user on the remote system who is invoking uudecode (typically uucp)
271 must have write permission on the file specified in the decode_path‐
272 name.
273 If you invoke uuencode and then execute uudecode on a file in the same
276 directory, you will overwrite the original file.
277SunOS 5.11 6 Aug 2003 uuencode(1C)