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Top Forums UNIX for Advanced & Expert Users Which cut command is more efficient? Post 302508647 by shamrock on Monday 28th of March 2011 03:55:23 PM
Old 03-28-2011
Quote:
Originally Posted by Corona688
Because it usually doesn't need to care about line boundaries. Stopping in the middle of a line won't make it "binary". (though cat without parameters ought to be binary-safe.) What blocks it does I/O in won't change the content of said I/O, a line too long for the block will just take a couple blocks to finish.
You are right...I was thinking about reading the file into a struct whose padding may get junk chars being output...but I was wrong. However here is a link to a recent version of cat and it does process cmd. line with and without flags differently.
 

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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)
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