Re: dd 4.1 EBCDIC conversion dialect

[Paul Eggert]

"Andrew M. Vick" <address@hidden> writes:

> Feature request: an option for the conv= argument to dd that sets
> the dialect.

I don't know of any standard name or catalog for EBCDIC<->ASCII
translation table variants.  Perhaps a volunteer could specify a
reasonable set of names and translation tables and submit a code and
documentation patch for them.  This wouldn't have to be a complete
table, so long as it was reliable within its domain.

> Bug: the dd man page does not say which EBCDIC dialect the GNU version
> of dd uses.

Thanks.  I installed the following patch to address this (and one
other) issue.  You can find the POSIX conversions at
<http://www.unix.org/version3/>, in the dd man page there.

2004-09-03  Paul Eggert  <address@hidden>

        * coreutils.texi (dd invocation): Specify which conversion options
        are mutually exclusive.  Give a bit more detail about ascii,
        ebcdic, and ibm conversions.

Index: coreutils.texi
===================================================================
RCS file: /home/eggert/coreutils/cu/doc/coreutils.texi,v
retrieving revision 1.202
retrieving revision 1.203
diff -p -u -r1.202 -r1.203
--- coreutils.texi      24 Aug 2004 07:37:28 -0000      1.202
+++ coreutils.texi      3 Sep 2004 08:00:48 -0000       1.203
@@ -6640,15 +6640,24 @@ Conversions:
 
 @item ascii
 @opindex address@hidden, converting to}
-Convert @acronym{EBCDIC} to @acronym{ASCII}.
+Convert @acronym{EBCDIC} to @acronym{ASCII},
+using the conversion table specified by @acronym{POSIX}.
+This provides a 1:1 translation for all 256 bytes.
 
 @item ebcdic
 @opindex address@hidden, converting to}
 Convert @acronym{ASCII} to @acronym{EBCDIC}.
+This is the inverse of the @samp{ascii} conversion.
 
 @item ibm
 @opindex alternate address@hidden, converting to}
-Convert @acronym{ASCII} to alternate @acronym{EBCDIC}.
+Convert @acronym{ASCII} to alternate @acronym{EBCDIC},
+using the alternate conversion table specified by @acronym{POSIX}.
+This is not a 1:1 translation, but reflects common historical practice
+for @samp{~}, @samp{[}, and @samp{]}.
+
+The @samp{ascii}, @samp{ebcdic}, and @samp{ibm} conversions are
+mutually exclusive.
 
 @item block
 @opindex block @r{(space-padding)}
@@ -6660,6 +6669,8 @@ input newline with a space and padding w
 Replace trailing spaces in each @samp{cbs}-sized input block with a
 newline.
 
+The @samp{block} and @samp{unblock} conversions are mutually exclusive.
+
 @item lcase
 @opindex address@hidden, converting to}
 Change uppercase letters to lowercase.
@@ -6668,6 +6679,8 @@ Change uppercase letters to lowercase.
 @opindex address@hidden, converting to}
 Change lowercase letters to uppercase.
 
+The @samp{lcase} and @samp{ucase} conversions are mutually exclusive.
+
 @item swab
 @opindex swab @r{(byte-swapping)}
 @cindex byte-swapping
@@ -6690,6 +6703,8 @@ Do not create the output file; the outpu
 @cindex creating output file, requiring
 Fail if the output file already exists; @command{dd} must create the
 output file itself.
+
+The @samp{excl} and @samp{nocreat} conversions are mutually exclusive.
 
 @item notrunc
 @opindex notrunc