Shell Programming and Scripting

Hi,

I have a for loop which iterates over a list of strings, separated by whitespace:

Code:

$ list="1 2 3"
$ for i in $list; do echo $i; done
1
2
3

I now want to introduce some strings containing whitespace themselves ... This is straightforward if I directly iterate over the list:

Code:

$ for i in 1\ 2 3; do echo $i; done
1 2
3

However, this does not work if the list is in a variable

Code:

$ list="1\ 2 3"
$ for i in $list; do echo $i; done
1\
2
3

Is there a way to somehow make the whitespace in the variable $list special, so that the for loop does not recognize it as a delimiter?

BTW: The for loop is not written by myself, but is burried deep in a build script I do not want to change ...

Thanks in advance!

Kai Koehne

You could try using set, e.g...

Code:

$ set "1 2" "3"
$ for i; do echo $i; done
1 2
3

$ set 1\ 2 3
$ for i; do echo $i; done
1 2
3

Note that it sets $1 $2 etc., so this may affect something else in your script.

hey there,

Setting

IFS=\n

at your bash prompt will set the delimiter a for loop uses to a newline.
eg with default IFS:
$ cat filelist
1 2 3
a b c


$ for i in `cat filelist` ; do echo $i ; done
1
2
3
a
b
c

$ IFS=\n
$ for i in `cat filelist` ; do echo $i ; done
1 2 3
a b c


Not super relevant to the first post as you can't choose the spot of the delimiter. but may help anyone stumbling along this post looking for an answer on how to change the delimiter a for loop is using.

In bash, I think this should be:
IFS=$'\n'

Also, you may want to store the old value of the environment variable IFS as overwriting it can potentially cause conflicts with other processes that use it.

-FJB

Thank you for this suggestion. It was very helpful for me.