BASH script bug?, simple maths... - maemo.org

Active Topics

Camera phone competition March 2023 "Endless" (35)
to General by Maemish - 1 day, 13 hrs ago
TLS 1.2 for N9 is ready (28)
to MeeGo / Harmattan by smartblu9 - 1 day, 15 hrs ago
Maemo repository (3)
to Community by torsen - 2 days, 6 hrs ago
Error after installing Leste on sdcard (11)
to Maemo 7 / Leste by Maemish - 3 days, 4 hrs ago
Introducing ubiboot N9 (multiboot OS loader) (1,393)
to Alternatives by smatkovi - 4 days, 10 hrs ago
more...

Page 1 of 2

Next >

Thread Tools

jamiefuller	2012-04-27 , 15:02
Posts: 145 \| Thanked: 304 times \| Joined on Jan 2010 @ Milton Keynes, UK	#1

Hi All,

I think i've found a little bug but would love for someone to confirm?

Basically I have this script

Code:

IN=00:08:19.12
IN=`echo $IN| cut -d'.' -f 1`

arr=$(echo $IN | tr ":" "\n")
a=0
for x in $arr
do
	echo $x
	a=$(( ( a * 60) + x ))
	echo $a
done

it should take IN and convert it into seconds.

This works on a unix box that I had access to but on the N900 I get the following error

Code:

Nokia-N900:/home/user/MyDocs# sh test
00
0
08
test: line 12: syntax error:  ( a * 60) + x

Could somebody recreate and confirm? or point out what I'm doing daft? =)

Thanks
jamie

UPDATE:

I've found that if I set IN to the following it works except for the lines in red italics? how wierd is that?

IN=00:00:19.12
IN=00:01:19.12
IN=00:02:19.12
IN=00:03:19.12
IN=00:04:19.12
IN=00:05:19.12
IN=00:06:19.12
IN=00:07:19.12
IN=00:08:19.12
IN=00:09:19.12
IN=00:10:19.12
IN=00:11:19.12
IN=00:12:19.12
IN=00:13:19.12
IN=00:14:19.12
IN=00:15:19.12
IN=00:16:19.12
IN=00:17:19.12
IN=00:18:19.12
IN=00:19:19.12
IN=00:20:19.12

Last edited by jamiefuller; 2012-04-27 at 15:08.

Quote & Reply |

	nicolai	2012-04-27 , 15:19
	Posts: 1,637 \| Thanked: 4,424 times \| Joined on Apr 2009 @ Germany	#2

08
Integers with leading "0" are interpreted as octal, so 08 is an illegal
octal number.
Remove the leading "0".

Nicolai

Quote & Reply |

The Following 7 Users Say Thank You to nicolai For This Useful Post:
Estel, jamiefuller, lma, misiak, pelago, reinob, szopin

jamiefuller	2012-04-27 , 15:32
Posts: 145 \| Thanked: 304 times \| Joined on Jan 2010 @ Milton Keynes, UK	#3

Originally Posted by nicolai

08
Integers with leading "0" are interpreted as octal, so 08 is an illegal
octal number.
Remove the leading "0".

Nicolai

Thanks Nicolai,

any chance of a code snipet as to how to remove the trailing zero?

Or just a better way of doing what I'm doing =)

Thanks
Jamie

Quote & Reply |

retsaw	2012-04-27 , 15:37
Posts: 701 \| Thanked: 585 times \| Joined on Sep 2010 @ London, England	#4

You can use bc to do the maths (you may need to install it)

Code:

	a=$(echo "( $a * 60 ) + $x" | bc )

Quote & Reply |

The Following 8 Users Say Thank You to retsaw For This Useful Post:
anthonie, don_falcone, Estel, jamiefuller, misiak, nicolai, reinob, szopin

jamiefuller	2012-04-27 , 15:52
Posts: 145 \| Thanked: 304 times \| Joined on Jan 2010 @ Milton Keynes, UK	#5

retsaw, that was perfect, thanks!

Quote & Reply |

gregoranderson	2012-04-27 , 16:40
Posts: 244 \| Thanked: 354 times \| Joined on Jul 2010 @ Scotland	#6

Following on from Nicolai's explanation - an alternative to using bc is to force bash to interpret the value as decimal, thus having the added option of the leading zero being chopped:

Code:

#!/bin/bash

LIFE=042

# Will return 34 as LIFE is interpreted as octal
echo $((LIFE))

# Force decimal representation
LIFE=$((10#${LIFE}))

# Should return the proper meaning of life 
echo $((LIFE))

Quote & Reply |

The Following 7 Users Say Thank You to gregoranderson For This Useful Post:
anthonie, don_falcone, Estel, misiak, nicolai, retsaw, szopin

retsaw	2012-04-27 , 16:58
Posts: 701 \| Thanked: 585 times \| Joined on Sep 2010 @ London, England	#7

Which while it works with bash, the N900 by default uses the ash shell built in to busybox and it doesn't work with that.

Quote & Reply |

The Following 3 Users Say Thank You to retsaw For This Useful Post:
Estel, gregoranderson, misiak

gregoranderson	2012-04-27 , 17:06
Posts: 244 \| Thanked: 354 times \| Joined on Jul 2010 @ Scotland	#8

Originally Posted by retsaw

Which while it works with bash, the N900 by default uses the ash shell built in to busybox and it doesn't work with that.

/me facepalms.

Fair point, well made! Apologies

Quote & Reply |

The Following 2 Users Say Thank You to gregoranderson For This Useful Post:
Estel, reinob

misiak	2012-04-27 , 18:07
Posts: 805 \| Thanked: 1,605 times \| Joined on Feb 2010 @ Gdynia, Poland	#9

Originally Posted by gregoranderson

/me facepalms.

Fair point, well made! Apologies

But the title of this threas states explicitly that this question is about bash, so no need to facepalm

Unless for OP "any shell"=="bash" which is a common misunderstanding (and a reason to facepalm for OP), but I doubt it

Quote & Reply |

The Following 6 Users Say Thank You to misiak For This Useful Post:
don_falcone, Estel, gregoranderson, reinob, retsaw, szopin

retsaw	2012-04-27 , 18:32
Posts: 701 \| Thanked: 585 times \| Joined on Sep 2010 @ London, England	#10

That point hadn't passed me by, but I also noted the error message was from Busybox's Ash shell as Bash gives a slightly different error. But I agree, there's no need for the facepalm, it was a useful post nonetheless and Bash was mentioned in the title.