For loop curiosity 1

[squash]

I have been writing a large script with many functions inside it.
At one point I had need to capture some text data and print to the screen.
I was surprised by the results I got and after some research time decided to change tactics.
Meaning I used another method to get the results I need.
However now that the script is finished and working I went back to my "for loop" issue to see if
I could figure out a way to make this work for future uses.
Maybe what I want/expect is not possible in this case?
It seems that "for" is parsing each item in the text file with space/tab separations.

I expected "new line" as the parse for each item.


I have two files:
1. Simple text file containing multiple lines.
Each line contains a command with arguments
2. A script that uses this text file

Text file = list.txt
Here is a two line sample
cat list.txt
./syncNode.sh ndm_${CELL} $PORT
./syncNode.sh ndm_${CELL}q $PORT

Script file = script.ksh
for i in `cat list.txt`
do
echo ""
echo "$i"
done

output of script.ksh

./syncNode.sh

ndm_${CELL}

$PORT

./syncNode.sh

ndm_${CELL}q

$PORT


Results I expected:

./syncNode.sh ndm_${CELL} $PORT

./syncNode.sh ndm_${CELL}q $PORT


Now I know in my example above the "for" loop is redundant as I could just cat the file.
However in my original script I was trying some more complex things inside the loop.
The "for" loop was NOT my best option, but at the time seemed prudent.
I was surprised at the output I got and now it is just a curiosity, not a needed exercise.
I am not looking for another way to accomplish, just like to learn how/why I got unexpected results.
The best I can figure is "for" ignores the carriage return and treats the file no different from:
for i in "1 2 3 4 5"
Be glad to hear any thoughts.
Thankx


As always we thank you for your support
Doug

 

[PHV]

The 'for ... in .. do ... done' parse words, not lines.
You may loop by rows like this:

while read i; do
  echo ""
  echo "$i"
done < list.txt

Furthermore, as you have variables (ndm_${CELL}) you may consider the eval builtin.

Hope This Helps, PH.
FAQ219-2884
FAQ181-2886

 

[SamBones]

To make it read the full line, put this before the loop...

unset IFS

The default IFS (Inter Field Separator I think), is whitespace (space or tab). You can also set it to something specific to parse fields as you need it. Example...

#!/bin/ksh

# Sample: oracle:x:100:100:Oracle Account:/home/oracle:/bin/ksh

# This makes the read get the full line
unset IFS

while read LINE
do
        # This makes the read parse the colon separated fields
        IFS=:

        print "${LINE}" | read USER PASS UID GID NAME HOMEDIR HOMESHELL

        print "${USER} = ${NAME}"
done < /etc/passwd

 

[PHV]

Sam, you don't need to unset IFS as you read a single variable ...

 

[PHV]

Furthermore, the default IFS is Space or Tab or LineFeed.

 

[squash]

Phv,
Your solution is one I had not considered as I used grep in my original solution.
Although looking at my code, i can see you use for future updates of this script.

Sambones,
I played with the IFS variable for my own leaning and found it difficult to wield the results I had expected.
I will certainly do more reading on this one again for possible future use.

Thankx
Doug


As always we thank you for your support
Doug

 

[squash]

just playing around a little I find that IFS will work like so:

IFS=$'\n'
for i in `cat list.txt`
do
echo ""
echo "$i"
done

Always fun to learn somthing as it is too easy to stick with what you know.




As always we thank you for your support
Doug