Spaces as line breaks from inline for loop command

Question

Someone care to enlighten me as to why the spaces in the first command seem to be interpreted as line breaks? Also occurs substituting print for echo.

$for l in $( find *.txt -exec head -1 {} \; ); echo $l;

9.16.11
09:20
9.19.11
18.41
9.21.11
07:15

$find *.txt -exec head -1 {} \;

9.16.11                 09:20
9.19.11                 18.41
9.21.11                 07:15

Solution 1

Check out the man page for your shell looking specifically at the IFS global variable.

Specifically, do this:

IFS=$(echo -en "\t\n\0")

Solution 2

Your command substitution induces word splitting on its output, based on IFS. Specifically, in this case it is splitting on spaces. Do not parse the output of find. Instead, do this:

for file in *.txt; do
    head -1 "${file}"
done

The Wooledge wiki also has some good information on this issue here.

Comments

[Christopher O'Neil]

echo $IFS | hexdump -c Has revealed $IFS to contain "\t \n \0 \n" But I'm still confused as to what I have to to keep the spaces from being interpreted as new lines?

[frogstarr78]

try hexdump -C there are actually 5 characters -c is displaying, the first is ' '

[clerksx]

@frogstarr78 - There's no need to use echo for that, in bash, just use $'\t\n\0'.

[frogstarr78]

@ChrisDown I didn't know. Thanx

[Peter.O]

This won't break: set -f; find . -name '*.txt' -print0 | while IFS= read -r -d $'\0' file; do head -1 "$file" ;done . . . The set -f disables pathname expansion