Script runs echo normally, but prints nothing for looped echo

matticebox

12/10/22, 6:04 AM

I'm trying to write a script that opens a terminal and loops echo in it. I have the following.

#!/usr/bin/bash

gnome-terminal -- /bin/bash -c "for i in 1 2 3; do echo $i; done; exec bash"

When I run this script, it shows three blank lines and then executes bash. However, if I run for i in 1 2 3; do echo $i; done; exec bash in a terminal it prints normally. Also, if I write the following it prints hello normally too. Therefore, I believe it's an issue with the for loop.

#!/usr/bin/bash

gnome-terminal -- /bin/bash -c "echo hello"

I couldn't find anyone with a similar issue.

0 + 7

bash

scripts

gnome-terminal

Ray

12/10/22, 6:26 AM

Why do you have `exec bash` at the end? I'm not sure if you want to run a loop within bash and then start another bash shell... Indeed, something is wrong with your code, but I can't put my finger on it... You're getting 3 blank lines because it is the value of `$i`. If, let's say, you put `i=10` and then run the loop, you'll get three `10` printed out, I think.

bac0n

12/10/22, 6:33 AM

you need single quotes or `$i` will evaluate, therefore ... empty lines

matticebox

12/10/22, 6:38 AM

@Ray I have `exec bash` at the end so I can look at the terminal after it loops echo. I was using sleep before, but I figured starting another bash shell would be easier. I'm a noob and don't really understand what you mean by `i=10`, but if i put `10` in place of `$i` it does indeed print `10` three times. It just doesn't make sense to me because when I run the code with `$i` in a terminal, it prints `1`, then `2`, then `3`. For example, `for i in hello; do echo $i; done` will print `hello` in a terminal.

matticebox

12/10/22, 6:41 AM

@bac0n I tried `gnome-terminal -- /bin/bash -c "for i in 1 2 3; do echo '$i'; done; exec bash"` and it still shows empty lines, unless I'm not noticing something else I've done wrong.

bac0n

12/10/22, 6:42 AM

no, `/bin/bash -c 'for i in 1 2 3; do echo $i; done; exec bash'`

matticebox

12/10/22, 6:44 AM

@bac0n It worked, thanks. But I don't understand what exactly is going on... I thought the usage of double and single quotes was just so you could have one inside the other.

Artur Meinild

12/10/22, 6:49 AM

[See here](https://stackoverflow.com/questions/6697753/difference-between-single-and-double-quotes-in-bash).

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Script runs echo normally, but prints nothing for looped echo

TH: สคริปต์เรียกใช้เสียงสะท้อนตามปกติ แต่ไม่พิมพ์สิ่งใดสำหรับเสียงก้องที่วนซ้ำ

RO: Scriptul rulează ecou în mod normal, dar nu imprimă nimic pentru ecou în buclă

RU: Скрипт запускает эхо нормально, но ничего не печатает для зацикленного эха

VI: Tập lệnh chạy tiếng vang bình thường, nhưng không in gì cho tiếng vang lặp

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