z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

v Environment variables (DBCS characters are not exportable).
v Delimiters such as space, slash (/), braces { }, tab, parentheses, dot (.), and any
other shell special characters.
v Encoding for newline or null cannot be embedded in a DBCS character’s code.
There are other rules that define valid DBCS data:
– The DBCS blank is 0x4040.
– The first byte of the code defining the DBCS character must be in the range
0x41 to 0xFE.
– The second byte must be in the range 0x41 to 0xFE.
All others are invalid. This effectively covers the newline and null escape
sequences, since they cannot be part of a valid DBCS character.
For more information on invalid DBCS characters, see Byte sequences that are
not permitted in DBCS strings.
v Although filenames with DBCS characters are tolerated, you should not create
filenames with DBCS characters. Doing so makes the file nonportable across
locales, and problems may occur if filenames are subsequently used in a
singlebyte locale. Instead, use the POSIX portable filename character set and
singlebyte filenames.
IBM will not support any customer problems with DBCS filenames.
For more information on DBCS filenames, see Problems with filenames
containing DBCS characters.
When you can use DBCS characters
When in the DBCS locale, you can use DBCS to specify the following:
v sh command-line arguments, although arguments expressed as numeric values
must use SBCS characters.
v Text in data files. Files containing DBCS text are processed correctly by the shell
and the utilities (such as ed and grep) if the DBCS locale is active. These files
can be either DBCS text or mixed text (combinations of SBCS and DBCS). Both
types of file can exist in the file system along with files that contain only
singlebyte text.
Byte sequences that are not permitted in DBCS strings
If you create invalid DBCS text, you may see an “illegal byte sequence” message
when processing that text. The shell or command issues this error message, and
the command stops processing in most cases.
Valid DBCS strings must start with “shift out” (SO [0x0E]) and end with “shift in” (SI
[0x0F]). The first byte of the code defining the DBCS character must be in the
range 0x41 to 0xFE. The second byte must be in the range 0x41 to 0xFE. The
exception is that DBCS blank is 0x4040. All others codes are invalid.
Normal terminal operations do not produce invalid DBCS strings. To prevent invalid
DBCS characters and strings:
v Do not use commands that operate on the data as byte strings instead of
character strings. For example, head is a utility that could truncate a DBCS string
or character in an inappropriate place, thus creating an invalid DBCS string.
Using pipes between utilities can also result in invalid DBCS strings unless you
pay attention to how each command handles the data.
v Do not edit text in nontext mode such as having the TSO/E editor with in HEX
ON mode.
8 z/OS V1R9.0 UNIX System Services Command Reference