topic Re: Really weird script problem in Operating System - Linux

Really weird script problem

John Atkinson_2 — Mon, 12 Sep 2005 20:04:28 GMT

When I run the following script the result depends on what directory I am in. The script is in /tmp.

#!/bin/sh

DATABASE=AP0041D

echo "1: [${DATABASE}]"
echo "2: [$DATABASE]"
echo 3: [${DATABASE}]
echo 4: [$DATABASE]

When run from any directory except / the output is:
$ ./quotes.sh
1: [AP0041D]
2: [AP0041D]
3: [AP0041D]
4: [AP0041D]

But from / the output is:
$ /tmp/quotes.sh
1: [AP0041D]
2: [AP0041D]
3: 1
4: 1

This only happens in HP-UX. I am using HP-UX 11.11 on PA-RISC. On several other versions of Unix (AIX and SuSE SLES 8), the output is the same as the first output even when run from /

Any ideas on how to prevent this inconsistency?

Re: Really weird script problem

Arunvijai_4 — Mon, 12 Sep 2005 23:50:29 GMT

Can you add set -vx in your script and execute in 11.11 (PA) ?

-- Arun

Re: Really weird script problem

John Atkinson_2 — Mon, 12 Sep 2005 23:56:52 GMT

run from / with set -vx

$ /tmp/quotes3.sh
DATABASE=AP0041D
+ DATABASE=AP0041D

echo "1: [${DATABASE}]"
+ echo 1: [AP0041D]
1: [AP0041D]
echo "2: [$DATABASE]"
+ echo 2: [AP0041D]
2: [AP0041D]
echo 3: [${DATABASE}]
+ echo 3: 1
3: 1
echo 4: [$DATABASE]
+ echo 4: 1
4: 1

Re: Really weird script problem

RAC_1 — Tue, 13 Sep 2005 00:00:58 GMT

Looks that script is doing what it is supposed to do. Posting of script will help.
Also make sure you define all required variables. Also in all variables, use ${XX}

Also set -u will error out, when it encounters unset variable.

Re: Really weird script problem

Stephen Keane — Tue, 13 Sep 2005 05:20:21 GMT

Do you, per chance, have a file in "/" named "1", if so (and if you can safely do so) can you remove it/rename it and re-run your script in "/"

Re: Really weird script problem

Muthukumar_5 — Tue, 13 Sep 2005 05:35:53 GMT

post information on,

# what /sbin/sh

#!/bin/sh

DATABASE=""

echo "1: [${DATABASE}]"
echo "2: [$DATABASE]"
echo 3: [${DATABASE}]
echo 4: [$DATABASE]

#!/bin/sh

DATABASE="AP0041D"

echo "1: [${DATABASE}]"
echo "2: [$DATABASE]"
echo 3: [${DATABASE}]
echo 4: [$DATABASE]

#!/bin/sh

DATABASE=A

echo "1: [${DATABASE}]"
echo "2: [$DATABASE]"
echo 3: [${DATABASE}]
echo 4: [$DATABASE]

hth.

Re: Really weird script problem

Arunvijai_4 — Tue, 13 Sep 2005 05:40:13 GMT

What stev specified is perfectly right. Just take a look at this.

# /tmp/weird.sh (executed from root)
1: [AP0041D]
2: [AP0041D]
3: [AP0041D]
4: [AP0041D]

# touch 1

# /tmp/weird.sh

1: [AP0041D]
2: [AP0041D]
3: 1
4: 1

# rm -f 1

# /tmp/weird.sh
1: [AP0041D]
2: [AP0041D]
3: [AP0041D]
4: [AP0041D]

Re: Really weird script problem

Stephen Keane — Tue, 13 Sep 2005 05:48:50 GMT

You'll find that if you have a file by the name of 'A', 'P', '0', '4', '1' or 'D' you'll get a similar effect. Do you see why?

Re: Really weird script problem

john korterman — Tue, 13 Sep 2005 06:15:18 GMT

Hi,

i "unprotected mode" i.e. if not protected by quotes, e.g. lines 3 and 4 in your script - the shell expands wildcards to filenames in thecurrent directory.
Compare:
# ls [AP041D]

which will match the file names A, P, 0, 4, 1, or D in the directory you are in.

regards,
John K.

Re: Really weird script problem

Zeev Schultz — Tue, 13 Sep 2005 06:19:15 GMT

man sh-posix:

"Braces are required when parameter is followed by a letter, digit, or underscore that should not be interpreted as part of its name or when a named parameter is subscripted. If parameter is one or more digits, it is a positional parameter.A positional parameter of more than one digit must be enclosed in braces."

And :

Inside double quote marks (""), parameter and command substitution occurs...

Meaning, last two echoes doesn't do the substitution...

Re: Really weird script problem

Orhan Biyiklioglu — Tue, 13 Sep 2005 06:31:44 GMT

Brackets are interpreted as wildcards by the shell unless they are quoted.
The shell will match files named with any of the characters between brackets. (Single char)

echo 3: [${DATABASE}] ==> echo 3: [AP0041D]

will match any files named
A, P, 0, 4, 1 or D

In your case, it seems you have a file named 1 in your / directory.