Why is my unix basic script does not do what I try to ? (How to write abc/1 abc/2 abc/3)

Question

I am doing this script (with zsh, but I guess that it is not very important):

mylist=`seq 1 3`
for i in $mylist ; do echo "abc/$i" ; done

This gives :

abc/1
2
3

while I would like to see :

abc/1
abc/2
abc/3

A huge thanks to somebody that may find why it does not work/how to do.

"with zsh, but I guess that it is not very important" in fact, it's very important. See for example zsh: What is word splitting? Why is it important in shell programming? — steeldriver, Jan 09 '21 at 20:48
@steedriver : you have a good point. Indeed, with bash, it works directly. Is there a way to make it work with zsh ? — Mathieu Krisztian, Jan 09 '21 at 21:13
As mentioned in the accepted answer to the Q&A linked above, you should consider using an array ex. mylist=( $(seq 1 3) ) (you can use backticks in place of $(...) for the command substitution if you prefer, however it is considered deprecated) — steeldriver, Jan 09 '21 at 21:37
ok got it. zsh does not split in general per design. very confusing — alecxs, Jan 09 '21 at 22:41
Note that you can also force the execution of your script to be in a POSIX-compatible fashion using the shebang line #! /bin/sh at the top of the file. Depending on your system this may run ksh/zsh/bash/dash/ash, but in any case in a mode that disables such features as the one which is causing this behavior. N.B. on most systems /bin/sh is not completely POSIX compatible, but usually good enough. — ljrk, Jan 10 '21 at 12:09
Quickest change to make it work with zsh could also be changing $mylist to ${=mylist}. That enables word splitting on the variable expansion. — JoL, Jan 10 '21 at 12:49

Bruce Malaudzi · Accepted Answer · 2021-01-09T21:38:09.757

5

You can keep it simple:

for i in 1 2 3; do echo "abc/$i" ; done

OR

for i in $(seq 1 3); echo "abc/$i"

Output:

abc/1
abc/2
abc/3

edited Jan 09 '21 at 21:38

answered Jan 09 '21 at 21:07

Bruce Malaudzi

sure thank you, but it was just an example : I really would like to use the "result of a unix commant with ..., not to cheat by putting by hand each value. – Mathieu Krisztian Jan 09 '21 at 21:10
excellent. Thanks a lot Bruce. Unfortunately, I'm new, else I would have given you at least 1000 points for your help. – Mathieu Krisztian Jan 09 '21 at 21:48
Thank you @MathieuKrisztian – Bruce Malaudzi Jan 09 '21 at 22:59

rm-vanda · Answer 2 · 2021-01-10T19:17:06.613

1

Another way to do this kinda thing is via brace expansion:

echo abc/{1..3}

But naturally, since you asked for newlines, you'd need to do it like this:

abc_strings=( abc/{1..3} )
printf "%s\n" "${abc_strings[@]}"

edited Jan 10 '21 at 19:17

answered Jan 10 '21 at 05:26

rm-vanda

score 0 · Answer 3 · answered Jan 10 '21 at 20:36

0

Just tried this in an online Zsh :

for i in `seq 1 3` 
do
echo "abc/$i\n"
done

Got the following:

abc/1
abc/2
abc/3

answered Jan 10 '21 at 20:36

Maximus Superbus

ah yes, thanks. But if you try with a variable, this creates a problem. – Mathieu Krisztian Jan 10 '21 at 20:39
In this case one does not need to create a variable, at least not in the example you have given. Defining it through the ticks (``) should suffice. – Maximus Superbus Jan 10 '21 at 20:42
(i had changed my message meanwhile) – Mathieu Krisztian Jan 10 '21 at 20:43
"this" is meaning the message of my question (for which there was a solution). There are problem with the editors : they don't print some characters. Anyway, see in my message : the inittial attempt was not working. mylist=seq 1 3 for i in $mylist ; do echo "abc/$i" ; done This gives : abc/1 2 3 – Mathieu Krisztian Jan 10 '21 at 20:44

3 Answers3