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Full Discussion: $(< file ) and $( cat file )
Top Forums Shell Programming and Scripting $(< file ) and $( cat file ) Post 303012380 by RudiC on Saturday 3rd of February 2018 03:27:56 AM
Old 02-03-2018
Quote:
Originally Posted by Scrutinizer
. . .
Code:
cat /dev/urandom -- tr -dc '[:alnum:],@#:!?+-' | head -c10

This is strange,
. . .
It is. In fact, tr -dc etc. are interpreted as input files
Code:
cat: tr: No such file or directory
cat: -dc: No such file or directory
cat: '[:alnum:],@#:!?+-': No such file or directory

and generate error messages which are suppressed in above case as /dev/urandom never ends and the pipe is chopped off by the head -c10 from the other side.
This User Gave Thanks to RudiC For This Post:
 

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CAT(1)							      General Commands Manual							    CAT(1)

NAME
cat - catenate and print SYNOPSIS
cat [ -u ] [ -n ] [ -s ] [ -v ] file ... DESCRIPTION
Cat reads each file in sequence and displays it on the standard output. Thus cat file displays the file on the standard output, and cat file1 file2 >file3 concatenates the first two files and places the result on the third. If no input file is given, or if the argument `-' is encountered, cat reads from the standard input file. Output is buffered in the block size recommended by stat(2) unless the standard output is a terminal, when it is line buffered. The -u option makes the output completely unbuffered. The -n option displays the output lines preceded by lines numbers, numbered sequentially from 1. Specifying the -b option with the -n option omits the line numbers from blank lines. The -s option crushes out multiple adjacent empty lines so that the output is displayed single spaced. The -v option displays non-printing characters so that they are visible. Control characters print like ^X for control-x; the delete char- acter (octal 0177) prints as ^?. Non-ascii characters (with the high bit set) are printed as M- (for meta) followed by the character of the low 7 bits. A -e option may be given with the -v option, which displays a `$' character at the end of each line. Specifying the -t option with the -v option displays tab characters as ^I. SEE ALSO
cp(1), ex(1), more(1), pr(1), tail(1) BUGS
Beware of `cat a b >a' and `cat a b >b', which destroy the input files before reading them. 4th Berkeley Distribution May 5, 1986 CAT(1)
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