Not a bug IMHO, but that may be open to debate. At least the observed behavior
conforms to the bash manual which reads:
- ((expression)) is strictly equivalent to: let "expression"
- parameter expansion is performed _before_ the expression is evaluated
Therefore, ((++a[$b])) translates to let "++a[$b]" which translates to
let "++a[80's]" which leads to an error.
The proper syntax would be (('++a[$b]')) which is admittedly quite
counter-intuitive. This way '$b' is evaluated as a whole during the
arithmetic evaluation.
Demonstration:
$ declare -A a
$ b="80's"
$ (('++a[$b]'))
$ printf '%s\n' "${!a[@]}" "${a[@]}"
80's
1
$ (('++a[$b]'))
$ printf '%s\n' "${!a[@]}" "${a[@]}"
80's
2
--
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to bash in Ubuntu.
https://bugs.launchpad.net/bugs/1618224
Title:
Single quote character not handled well in associative array index
Status in bash package in Ubuntu:
New
Bug description:
Say you have script named test.sh in current directory
#!/bin/bash
declare -A a
b="80's"
((++a[$b]))
((++a["$b"]))
[[ $((++a[$b])) ]] || true
[[ $((++a["$b"])) ]] || true
echo ${a["$b"]}
echo ${a[$b]}
It outputs
./test.sh: line 4: ((: ++a[80's]: bad array subscript (error token is
"a[80's]")
./test.sh: line 5: ((: ++a[80's]: bad array subscript (error token is
"a[80's]")
./test.sh: line 6: ++a[80's]: bad array subscript (error token is "a[80's]")
1
1
Expected output is
4
4
like it is when b is "80s". Note that only the incremention on line 7 of the
script works.
This bug also happens by bash 4.3-7ubuntu1.5 (Trusty)
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: bash 4.3-14ubuntu1.1
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: XFCE
Date: Tue Aug 30 00:24:58 2016
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-11-21 (282 days ago)
InstallationMedia: Xubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: bash
UpgradeStatus: Upgraded to xenial on 2016-06-24 (66 days ago)
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1618224/+subscriptions
--
Mailing list: https://launchpad.net/~touch-packages
Post to : touch-packages@lists.launchpad.net
Unsubscribe : https://launchpad.net/~touch-packages
More help : https://help.launchpad.net/ListHelp
