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Full Discussion: $(< file ) and $( cat file )
Top Forums Shell Programming and Scripting $(< file ) and $( cat file ) Post 303012384 by ctsgnb on Saturday 3rd of February 2018 04:27:16 AM
Old 02-03-2018
Yeah, I agree with you regarding the UUOC one.
The test with -- was just bulk try just to see if it would get the -- as an end of options and see how it would handle the rest of the command line.

I ran it on an AIX machine which didn't return an error message, but a fooled output instead, with some strange control character (the kind of output that sometimes may mess up your PuTTY screen ...)

As Yoda and Scruti noticed, I think the confusing point was that, $(< /dev/urandom tr -dc '[:alnum:],@#:!?+-' | head -c10 )
is not interpreted as the special case $(<filename) but as the $( cmd )

This brings me to the question :
Does the special case $(<filename) support only and strictly 1 file ?
Last edited by ctsgnb; 02-03-2018 at 05:37 AM..
 

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LEARN ABOUT CENTOS

iswalnum

ISWALNUM(3)						     Linux Programmer's Manual						       ISWALNUM(3)

NAME

       iswalnum - test for alphanumeric wide character

SYNOPSIS

       #include <wctype.h>

       int iswalnum(wint_t wc);

DESCRIPTION

       The  iswalnum() function is the wide-character equivalent of the isalnum(3) function.  It tests whether wc is a wide character belonging to
       the wide-character class "alnum".

       The wide-character class "alnum" is a subclass of the wide-character class "graph", and therefore also a  subclass  of  the  wide-character
       class "print".

       Being a subclass of the wide-character class "print", the wide-character class "alnum" is disjoint from the wide-character class "cntrl".

       Being  a  subclass  of the wide-character class "graph", the wide-character class "alnum" is disjoint from the wide-character class "space"
       and its subclass "blank".

       The wide-character class "alnum" is disjoint from the wide-character class "punct".

       The wide-character class "alnum" is the union of the wide-character classes "alpha" and "digit".  As such, it also contains the	wide-char-
       acter class "xdigit".

       The wide-character class "alnum" always contains at least the letters 'A' to 'Z', 'a' to 'z' and the digits '0' to '9'.

RETURN VALUE

       The  iswalnum()	function  returns  nonzero  if wc is a wide character belonging to the wide-character class "alnum".  Otherwise it returns
       zero.

CONFORMING TO

       C99.

NOTES

       The behavior of iswalnum() depends on the LC_CTYPE category of the current locale.

SEE ALSO

       isalnum(3), iswctype(3)

COLOPHON

       This page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    1999-07-25							       ISWALNUM(3)
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