11-15-2005
file reading in unix
Hi ,
I need to read line by line from a file. Can u please tell me the most efficient way to do it. SInce i will be reading more than 1000 files in my program. i am trying the following options :
1. nawk option
nawk'{
print $0
}'files.temp
2.
filecount=`cat files.temp | wc -l`
i=1
while [ $i -le $filecount ]
do
filename=`cat files.temp | head -$i | tail -1`
#echo $filename
done
can u please tell me the best way to do this.
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CAT(1) General Commands Manual CAT(1)
NAME
cat - catenate and print
SYNOPSIS
cat [ -u ] [ -n ] [ -s ] [ -v ] file ...
DESCRIPTION
Cat reads each file in sequence and displays it on the standard output. Thus
cat file
displays the file on the standard output, and
cat file1 file2 >file3
concatenates the first two files and places the result on the third.
If no input file is given, or if the argument `-' is encountered, cat reads from the standard input file. Output is buffered in the block
size recommended by stat(2) unless the standard output is a terminal, when it is line buffered. The -u option makes the output completely
unbuffered.
The -n option displays the output lines preceded by lines numbers, numbered sequentially from 1. Specifying the -b option with the -n
option omits the line numbers from blank lines.
The -s option crushes out multiple adjacent empty lines so that the output is displayed single spaced.
The -v option displays non-printing characters so that they are visible. Control characters print like ^X for control-x; the delete char-
acter (octal 0177) prints as ^?. Non-ascii characters (with the high bit set) are printed as M- (for meta) followed by the character of
the low 7 bits. A -e option may be given with the -v option, which displays a `$' 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)