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List:       perl-win32-users
Subject:    Can't use $\ to force line termination to 0x0a
From:       "L. Neil Johnson" <neiljohn () xmission ! com>
Date:       2005-02-24 6:51:15
Message-ID: 01C51A02.9070DE60.neiljohn () xmission ! com
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An MS-DOS batch file launches a PERL script which calculates input 
specifications for a filter-design program written in FORTRAN running under 
cygwin's shell for MS-DOS.  The specifications are written by PERL to many 
text-files which are read by the UNIX-based program. Therein lies the 
problem. PERL for Win32 writes the line terminators as CRLF (0x0d0a), and 
the UNIX-based program blows up reading the "unexpected character" CR. What 
we want to do is write LF (0x0a) as the text-file termination character. 
 Simple, no?

PerFunc documentation for binmode() says: "See the $/ and $\ variables in 
the perlvar manpage for how to manually set your input and output 
line-termination sequences." The PerlVar documentation for $\ says: 
"Ordinarily the print operator simply prints out its arguments as is, with 
no trailing newline or other end-of-record string added. To get behavior 
more like awk, set this variable as you would set awk's ORS variable to 
specify what is printed at the end of the print. (Mnemonic: you set $\ 
instead of adding ``\n'' at the end of the print..."

So we did what it what it said (I hope). LineTermTest.plx tests different 
combinations of $\ and \n. No configuration produces the desired LF 
termination.

# 'print' Line Termination Test
#  Use "od -Ad -txz <fname" to display hex dump of output

# 1. What is the default setting of $\?
#  ($\ is a scalar that contains a string.)
$BS = $\;
if (defined ($BS)) {print ("$BS")}  # Can't use $\ before double-quote
else {print "\$\\ undefined on entry.\n"}
# Output: "$\ undefined on entry."

# 2. String with default $\ but no \n
print ("A");
# Output: 0x41       [no termination]

# 3. String with default $\ and \n
print ("B\n");
# Output: 0x420d0a   [B followed by CRLF]

# 4. String with $\="\x0a", no \n
# Backslash escape to insert hex value in double-quoted string
$\ = "\x0a";
print ("C");
# Output: 0x430d0a   [C followed by CRLF]

# 5. String with $\="\x0a" and \n
print ("D\n");
# Output: 0x440d0a   [D followed by CRLF]

# 6. String with embedded LF, no \n
print ("E\x0a");
# Output: 0x450d0a   [E followed by CRLF]


Is $\ being overridden? It appears that even though $\="\x0a" may terminate 
print lines with LF, this character is replaced by CRLF at a lower layer 
before output to the file.

Does $\ work as advertised under W32? Sorry for using the -v option :-) 
 Thank you, Neil

Environment: W98SE, ActiveState PERL for MSWin32-x86-multi-thread, build 
631, 1/2/2002.
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