bash: can't set a variable to a solid string

Question

I cannot set a variable with a whole command-string as following:

A="/bin/ps wwwaux"

for a in $A
do
  echo "$a"
done

It assigns array instead of solid string someway.

My environment:

GNU/Linux, GNU bash, version 3.2.51(1)-release (x86_64-suse-linux-gnu)

I know this is a duplicate of a previously asked and answered question, but my search skills are failing me and I can't find the previous question. — John, May 29 '15 at 16:06
You mean you want to save output of `/bin/ps wwwaux` into variable `A`? — cuonglm, May 29 '15 at 16:09
@cuonglm NO. I want to put command-string as it is, with spaces, to A variable. — user1065145, May 29 '15 at 16:15

score 8 · Answer 1 · answered May 29 '15 at 16:32

The for loop expects a list:

for a in $A; do
  echo "$a"
done

Expands to:

for a in /bin/ps wwwaux; do
  echo "$a"
done

Which prints both after each other. The loop runs twice, because there are TWO arguments. The output will be:

/bin/ps
wwwaux

Use quotes instead:

for a in "$A"; do
  echo "$a"
done

This will expands to:

for a in "/bin/ps wwwaux"; do
  echo "$a"
done

Which will loop exactly once, because it's ONE argument. That's the output:

/bin/ps wwwaux

John · Answer 2 · 2015-05-29T16:16:57.950

5

for f in "$A"
do
  echo $f
done

Your assignment is already doing what you want - it's the "for" loop that's breaking it up in a way you don't want.

edited May 29 '15 at 16:16

answered May 29 '15 at 16:05

John

2 Answers2