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oliver

Member

Registered: 2007-12-12

Posts: 448

[solved] bash - is this a result of the shellshock patches?

... or just something I've never noticed before

$ cat weird.sh 
#!/usr/bin/bash

testfunc() {
  echo "test inside function $1"
}

echo "test outside function $1"
testfunc

$ ./weird.sh arg1
test outside function arg1
test inside function 

$ bash --version
GNU bash, version 4.3.26(1)-release (x86_64-unknown-linux-gnu)

I was expecting $1 to be returned from the function too (and it does work if I add $1 as a variable - i,e. ARG=$1)

Last edited by oliver (2014-09-29 21:21:29)

aiBo

Member

Registered: 2010-11-10

Posts: 50

Re: [solved] bash - is this a result of the shellshock patches?

Works as it always has. Function invocation resets the positional paramters to the passed arguments. So, since you didn't pass any arguments to the function, $1 is empty inside the function block.

See 'set' in the 'SHELL BUILTIN COMMANDS' section in the bash manual page.

Last edited by aiBo (2014-09-29 21:12:44)

WorMzy

Administrator

From: Scotland

Registered: 2010-06-16

Posts: 13,438

Website

Re: [solved] bash - is this a result of the shellshock patches?

just something I've never noticed before

This.

As aiBo explained, you're not passing anything to the function, so $1 is not set inside it.

To further elaborate on this, what would you expect the output of the following to be?:

$ cat weird.sh
#!/usr/bin/bash

testfunc() {
  echo "test inside function $1"
}

echo "test outside function $1"
testfunc abc

$ ./weird.sh arg1

Last edited by WorMzy (2014-09-29 21:22:59)

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oliver

Member

Registered: 2007-12-12

Posts: 448

Re: [solved] bash - is this a result of the shellshock patches?

Works as it always has. Function invocation resets the positional paramters to the passed arguments. So, since you didn't pass any arguments to the function, $1 is empty inside the function block.

See 'set' in the 'SHELL BUILTIN COMMANDS' section in the bash manual page.

Thanks!  Makes perfect sense now

oliver

Member

Registered: 2007-12-12

Posts: 448

Re: [solved] bash - is this a result of the shellshock patches?

To further elaborate on this, what would you expect the output of the following to be?:

yeah - I see what you mean and I appreciate the further elaboration

ezzetabi

Member

Registered: 2006-08-27

Posts: 947

Re: [solved] bash - is this a result of the shellshock patches?

I have been told this code show the vunerability:

$ env x='() { :;}; echo vulnerable' bash -c "echo this is a test"