iconv.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" Copyright (C) BULL, Digital Equipment Co., SIEMENS 1986,1987,1988
.\" SCCSID: @(#)iconv.1	19.1 89/01/19
.TH iconv 1
.SH Name 
iconv \- international codeset conversion
.SH Syntax
.B iconv
[\fB\-d\fR] \fB-f\fR \fIfromcodeset\fR \fB-t\fR \fItocodeset\fR [\fIfile...\fR]
.br
.SH Description
The
.PN iconv
command converts the encoding of characters in its input
from one codeset to another codeset.  The \fIfromcodeset\fP
argument specifies the codeset used to encode the data in the input;
that is, it specifies the input codeset.  The \fItocodeset\fP
argument specifies the codeset to which you want the input data 
converted; that is, it specifies the output codeset.
The 
.PN iconv
command performs the conversion by reading rules from a
conversion table you
create.  The command reads its input from standard input or from one or more 
files named on the command line.
The command writes its output to standard output.
.PP
You define conversion rules in a
conversion table. The conversion rules specify how 
.PN iconv
converts a particular character 
or group of characters, which are called tokens. 
The conversion table is a text file that contains two lists.
In the left-hand list, you specify each token you want 
.PN iconv
to convert.  In the right-hand list, you specify the token you want
.PN iconv
to create in the output file. For example, if you issued the following 
command:
.EX
% iconv \-fupper \-tlower conversion_file
.EE
.PP
This command uses the conversion table located in the file 
.PN /usr/lib/intln/conv/upper_lower , 
that specifies how to convert from an uppercase codeset to a lowercase 
codeset. The following shows part of the conversion table: 
.EX 0
#
# Converts from uppercase to lowercase
#
#	Input token		Output token
#	-------------		------------------
	     A				a
	     B				b
	     C				c
	     D				d
	     E				e
	     F				f
	     G				g
          .
          .
          .
	     Z				z
#
# Convert tabs to spaces using octal
#
	    \\011		       \\040\\040\\040
#
# Convert the A umlaut to lowercase
#
             A\(..                        a\(..
.EE
.PP
Each line in the conversion table must contain two strings, an input token and
an output token.  The tokens must be delimited with spaces or tabs.
The backslash
character ( \\\ ) either causes the 
.PN iconv
command to recognize a character it normally ignores or introduces
a three digit octal constant.  All octal constants in the conversion
table must contain three digits.  
Lines that begin with a hash symbol (#) are comments.
The 
.PN iconv 
command ignores comment lines and blank lines.  
.PP
You name the conversion table file using the name of the input
codeset, an underscore, and the name of the output codeset.
For example, if your input codeset is ISO646 and your output codeset is 
ISO8859, you might name the conversion table file
.PN 646_8859 .
.PP
The 
.PN iconv
command searches for the conversion table file in the directory specified by
the 
.PN ${ICONV}/conv
pathname.
If the ${ICONV} environment variable is undefined,
the 
.PN iconv
command searches the 
.PN /usr/lib/intln/conv
directory. 
.PP
The operation of the 
.PN iconv
command is 8-bit transparent.
.SH Options
.IP \fB\-d\fR 0.3i
Deletes any characters that are omitted from the conversion table.
By default, the
.PN iconv
command sends characters that are omitted to the output file without 
modifying them.
.IP \fB\-f\fR 0.3i
Specifies the name of the input codeset.
.IP \fB\-t\fR 0.3i
Specifies the name of the output codeset.
.SH Restrictions  
The conversion table file name can contain no more than 255 characters.
You may need to truncate the name of the input codeset or output codeset 
when you name the conversion table file.
.SH Examples 
The following shows an example of using the 
.PN iconv
command:
.EX 0
.UI "% " "iconv \-f646 \-t8859 mydatafile > newdatafile"
.EE
.PP
This command converts the data in
.PN mydatafile
from ISO646 encoding to ISO8859
encoding.  The 
.PN iconv 
command reads the conversion table from the 
.PN ${ICONV}/conv/646_8859
file.  If the ${ICONV} environment variable is undefined, the
.PN iconv
command uses the
.PN /usr/lib/intln/conv/646_8859 
file. If that file does not exist, the 
.PN iconv
command issues an error message and does not convert the data file.
The 
.PN iconv
command writes the results  of any conversion it performs to the file
.PN newdatafile
.SH Files
.PN /usr/lib/conv/\fIfromcodeset_tocodeset\fP
.br
.PN ${ICONV}/conv/\fIfromcodeset_tocodeset\fP
.SH See Also
environ(5int) 
.br
\fIGuide to Developing International Software\fP