09-04-2012
As others mentioned, read reads lines from standard input. In this case, standard input is coming from the here-document. Hence, read will always read from the here-doc. read will wait for the input (until a time either specified by TMOUT or that overridden by -t option) provided the source (in this case, the here-doc) has not been "exhausted". In your case, after printing out Betty, the here-doc has been "exhausted" and read tries to read from this source and reads a null value with an exit status of 1 and since you have not specified any exit condition for the loop for this case, the loop just prints out the null value of line.
Last edited by elixir_sinari; 09-04-2012 at 03:26 AM..
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LEARN ABOUT DEBIAN
plan9-cat
CAT(1) General Commands Manual CAT(1)
NAME
cat, read, nobs - catenate files
SYNOPSIS
cat [ file ... ]
read [ -m ] [ -n nline ] [ file ... ]
nobs [ file ... ]
DESCRIPTION
Cat reads each file in sequence and writes it on the standard output. Thus
cat file
prints a file and
cat file1 file2 >file3
concatenates the first two files and places the result on the third.
If no file is given, cat reads from the standard input. Output is buffered in blocks matching the input.
Read copies to standard output exactly one line from the named file, default standard input. It is useful in interactive rc(1) scripts.
The -m flag causes it to continue reading and writing multiple lines until end of file; -n causes it to read no more than nline lines.
Read always executes a single write for each line of input, which can be helpful when preparing input to programs that expect line-at-a-
time data. It never reads any more data from the input than it prints to the output.
Nobs copies the named files to standard output except that it removes all backspace characters and the characters that precede them. It is
useful to use as $PAGER with the Unix version of man(1) when run inside a win (see acme(1)) window.
SOURCE
/src/cmd/cat.c
/src/cmd/read.c
/bin/nobs
SEE ALSO
cp(1)
DIAGNOSTICS
Read exits with status eof on end of file or, in the -n case, if it doesn't read nlines lines.
BUGS
Beware of and which destroy input files before reading them.
CAT(1)