Re: rewriting a readonly var should exit

[John McKown]

Are you running BASH in POSIX mode? That's a option.

Example:

[tsh009@it-johnmckown-linux junk]$ cat ro.sh

#!/bin/bash

readonly x="x"

x="y"

echo "sno"

[tsh009@it-johnmckown-linux junk]$ ./ro.sh 

./ro.sh: line 3: x: readonly variable

sno

[tsh009@it-johnmckown-linux junk]$ vim ro.sh

[tsh009@it-johnmckown-linux junk]$ cat ro.sh

#!/bin/bash

set -o posix

readonly x="x"

x="y"

echo "sno"

[tsh009@it-johnmckown-linux junk]$ ./ro.sh

./ro.sh: line 4: x: readonly variable

[tsh009@it-johnmckown-linux junk]$ 

On Tue, Dec 15, 2015 at 5:12 AM, Aurelien ROUGEMONT <beorn@gandi.net> wrote:

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu'
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash'
-DSHELL -DHAVE_CONFIG_H   -I.  -I../. -I.././include -I.././lib
-D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector-strong -Wformat
-Werror=format-security -Wall
uname output: Linux clamavsig1 3.16.0-4-amd64 #1 SMP Debian
3.16.7-ckt11-1+deb8u6 (2015-11-09) x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.3
Patch Level: 30
Release Status: release

Description:
        in the posix shell specification [1] when a script tries to to
overwrite a readonly variable it should crash the script.

Repeat-By:
        #!/bin/bash
        readonly rovar="goodvalue"
        rovar="badvalue"
        echo "You should not see this message"

Fix:
        the bash interpreter should exit when the readonly var is being asked
for an overwrite



[1]
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_08_01



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