Re: Howto read file line-by-line in bash

On Mar 20, 6:04 am, Viatly <postoronnim...@xxxxxxx> wrote:
On 20 mrt, 10:49, Stephane CHAZELAS <this.addr...@xxxxxxxxxx> wrote:



2008-03-20, 02:38(-07), Viatly:

The content of test.data is

-bash-3.2# cat test.data
line1
line2
line3
It is important that there is no trailing EOL at the end of file.
I read test.data with the following script:

-bash-3.2# cat test.sh
#!/bin/bash
while read line
do
echo "$line"
done < "test.data"

-bash-3.2# ./test.sh
line1
line2

That is, "line3" is lost.
Questions:
1. What is a nice way to fix this code?

The nicest way is to avoid while read loops in shells.

Why? In fact what I need is
while read line
do
# do some processing
done < "test.data"





2. The code of the script pretends to be a stdandard way if reading
text file line-by-line because it is recommended by respected
resources (e.g.http://bash-hackers.org/wiki/doku.php/tests/bashfaq).
Provided the code is ok, does it mean that a typical text file in Unix/
Linux should have EOL at the end?

"read" returns false if a full line is not read, but $line will
contain those extra characters after the last NL character

while IFS= read -r line; do
printf '%s\n' "$line"
done < test.data
printf %s "$line"

Will do it, but

cat test.data

Do you mean:

for line in `cat test.data`;
do
echo $line;
done

In this case if the line contains words separated by a whitespace,
this whitespace will be used as a separator. Which I do not need.



Note that a file that doesn't end in a NL character is not a
text file as per the POSIX definition of a text file. (that
means for instance that the behavior of a text utility
processing it is unspecified most of the time).

This is good argument. So, the problem is not in code, but rather in
ill-formed text file. Right?

--
Stéphane

Hi Viatly,

Try using this..

OLDIFS=$IFS
IFS="|"
for line in `cat test.data`;
do
echo $line;
done
IFS=$OLDIFS

This is simple and crisp.

Rgds
Gaurav S
.

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