[SOLVED] bash loop not working as expected...

replica9000 · 04-23-2011, 07:39 PM

Code:

#!/bin/sh

BASH=$(bash --version | grep -m1 version)

echo "$BASH"
for H in {0..85}
do
echo "Counting Line $H"
done
exit 0

GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)
Counting Line {0..85}

Isn't this supposed to show a result like this:
Counting Line 1
Counting Line 2
Counting Line 3
Counting Line 4
....
Counting Line 85

TobiSGD · 04-23-2011, 07:44 PM

I tested that little script for you, and are getting exactly the output you expected.

replica9000 · 04-23-2011, 07:47 PM

All I get is

Code:

GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)
Counting Line {0..85}

TobiSGD · 04-23-2011, 07:52 PM

I copy and pasted your script into the file test.sh, made it executable and then started it. This is the output:

Code:

tobi@dragon ~ :) % ./test.sh 
GNU bash, version 4.1.10(2)-release (i486-slackware-linux-gnu)
Counting Line 0
Counting Line 1
Counting Line 2
Counting Line 3
Counting Line 4
Counting Line 5
Counting Line 6
Counting Line 7
Counting Line 8
Counting Line 9
Counting Line 10
Counting Line 11
Counting Line 12
Counting Line 13
Counting Line 14
Counting Line 15
Counting Line 16
Counting Line 17
Counting Line 18
Counting Line 19
Counting Line 20
Counting Line 21
Counting Line 22
Counting Line 23
Counting Line 24
Counting Line 25
Counting Line 26
Counting Line 27
Counting Line 28
Counting Line 29
Counting Line 30
Counting Line 31
Counting Line 32
Counting Line 33
Counting Line 34
Counting Line 35
Counting Line 36
Counting Line 37
Counting Line 38
Counting Line 39
Counting Line 40
Counting Line 41
Counting Line 42
Counting Line 43
Counting Line 44
Counting Line 45
Counting Line 46
Counting Line 47
Counting Line 48
Counting Line 49
Counting Line 50
Counting Line 51
Counting Line 52
Counting Line 53
Counting Line 54
Counting Line 55
Counting Line 56
Counting Line 57
Counting Line 58
Counting Line 59
Counting Line 60
Counting Line 61
Counting Line 62
Counting Line 63
Counting Line 64
Counting Line 65
Counting Line 66
Counting Line 67
Counting Line 68
Counting Line 69
Counting Line 70
Counting Line 71
Counting Line 72
Counting Line 73
Counting Line 74
Counting Line 75
Counting Line 76
Counting Line 77
Counting Line 78
Counting Line 79
Counting Line 80
Counting Line 81
Counting Line 82
Counting Line 83
Counting Line 84
Counting Line 85
tobi@dragon ~ :) %

To make sure that this is not a shell related problem (I am using zsh instead of bash) I also started it with

Code:

bash test.sh

This gave the same output.

j1alu · 04-23-2011, 07:56 PM

but it does not work with:
#!/bin/sh
when not called with "bash name_of.sh".
replace it with:
#!/usr/bin/env bash
and it should work.

I figured it out by testing, not by knowing. So it might well be wrong.

replica9000 · 04-23-2011, 08:00 PM

Ok it works if I do
bash ./myscript

doesn't work if I just type
./myscript

Is there something wrong here??

replica9000 · 04-23-2011, 08:10 PM

Quote:

Originally Posted by j1alu

but it does not work with:
#!/bin/sh
when not called with "bash name_of.sh".
replace it with:
#!/usr/bin/env bash
and it should work.

I figured it out by testing, not by knowing. So it might well be wrong.

This works too. I've only ever started scripts with #!/bin/sh and it's never failed me until now.

maine_guy · 04-24-2011, 01:09 AM

You probably are invoking dash instead of bash. Check this with
ls -l `which sh`

If sh is a symbolic link to dash, change it to bash:
cd /bin
sudo rm sh
sudo ln -s bash sh

then try your script again.

dudeman41465 · 04-24-2011, 02:03 AM

Change the first line of the script to:

Code:

#!/bin/bash

When I just tried doing ./test.sh I got the same weird output, however when I changed the first line to specify bash, then ran the script, I got the expected output of:

Code:

Counting Line 0
Counting Line 1
Counting Line 2
Counting Line 3
Counting Line 4
........

replica9000 · 04-24-2011, 02:24 AM

Quote:

Originally Posted by maine_guy

You probably are invoking dash instead of bash. Check this with
ls -l `which sh`

If sh is a symbolic link to dash, change it to bash:
cd /bin
sudo rm sh
sudo ln -s bash sh

then try your script again.

Exactly what was happening, made the switch...

Thanks

MTK358 · 04-24-2011, 09:08 AM

If this is solved, mark the thread as solved.