Elements in a "for loop" using bash not being separated by white spaces.

ralste · 11-09-2009, 08:50 AM

Hai da, together!!
Consider a file and a "for loop" over its elements.
$ cat file1
one
two
three four
five
$ for x in `cat file1`; do echo $x; done
one
two
three
four
five
How to get the "for loop" done to get the elements by line, means...
$ for x in `???`; do echo $x; done
one
two
three four
five
Thousands of thanks for any help...

Guttorm · 11-09-2009, 08:59 AM

You can use while instead of for:

cat file1 | while read x ; do echo $x ; done

tuxdev · 11-09-2009, 01:17 PM

This is better and eliminates that UUOC (useless use of cat). Also allows variables set inside the loop to stay that way outside the loop which is what is usually expected:

Code:

while read -r LINE ; do
   :
done < "$FILE"

chrism01 · 11-09-2009, 11:26 PM

Set the IFS var to newline only http://tldp.org/LDP/abs/html/internalvariables.html, then you can use a for loop.

ghostdog74 · 11-09-2009, 11:41 PM

Quote:

Originally Posted by ralste

Hai da, together!!
Consider a file and a "for loop" over its elements.
$ cat file1
one
two
three four
five
$ for x in `cat file1`; do echo $x; done
one
two
three
four
five
How to get the "for loop" done to get the elements by line, means...
$ for x in `???`; do echo $x; done
one
two
three four
five
Thousands of thanks for any help...

learn how to use awk to parse files. see my sig for gawk manual.

catkin · 11-10-2009, 01:55 AM

Quote:

Originally Posted by chrism01

Set the IFS var to newline only http://tldp.org/LDP/abs/html/internalvariables.html, then you can use a for loop.

What are the advantages of that technique over tuxdev's suggestion in this case?

ghostdog74 · 11-10-2009, 02:26 AM

Quote:

Originally Posted by catkin

What are the advantages of that technique over tuxdev's suggestion in this case?

no advantage. One must take care to set IFS back to normal else it may cause problems elsewhere in the script. Using while read is still better in that respect.