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-unknown-linux-gnu'
-DCONF_VENDOR='unknown' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash'
-DSHELL -DHAVE_CONFIG_H -I. -I. -I./include -I./lib
-D_FORTIFY_SOURCE=2 -march=x86-64 -mtune=generic -O2 -pipe
-fstack-protector-strong --param=ssp-buffer-size=4
-DDEFAULT_PATH_VALUE='/usr/local/sbin:/usr/local/bin:/usr/bin'
-DSTANDARD_UTILS_PATH='/usr/bin' -DSYS_BASHRC='/etc/bash.bashrc'
-DSYS_BASH_LOGOUT='/etc/bash.bash_logout'
uname output: Linux manji 3.19.0-gbfa76d49 #28 SMP Mon Feb 9 14:29:14
CET 2015 x86_64 GNU/Linux
Machine Type: x86_64-unknown-linux-gnu
Bash Version: 4.3
Patch Level: 33
Release Status: release
Description:
when dealing with integer operations(let, ++), "bad array subscript"
errors can happen because subscripts get unquoted (and evaluated even
though they are in single quotes); unlike what happens when dealing with
strings.
Repeat-By:
please see attached bash script to reproduce because that explains it
much better than I could in words.
Thank you.
#!/bin/bash
#tested under: GNU bash, version 4.3.33(1)-release (x86_64-pc-linux-gnu) of Gentoo Linux, package: app-shells/bash-4.3_p33-r1
# also tested on the same version on Linux Manjaro: GNU bash, version 4.3.33(1)-release (x86_64-unknown-linux-gnu) /usr/bin/bash is owned by bash 4.3.033-1, /bin -> usr/bin/
set -u
set -x
set +e
declare -A ar=()
idgood="goodstring"
idbad1="bad string"
idbad2="["
let ar[$idgood]+=1 #works
echo "${ar[$idgood]}"
let ar['$idbad1']+=12 #works but it's a workaround
echo "${ar[$idbad1]}"
let ar['$idbad2']+=33 #works but it's a workaround
echo "${ar[$idbad2]}"
let ar[$idbad1]+=44 #fail: + let 'ar[bad' 'string]+=44'
#./subscripty_integer.bash: line 21: let: ar[bad: bad array subscript (error token is "ar[bad")
let ar[$idbad2]+=55 #fail: + let 'ar[[]+=55'
#./subscripty_integer.bash: line 24: let: ar[[]+=55: bad array subscript (error token is "ar[[]+=55")
ar["$idbad1"]+=12 #works but it's considered as string which makes sense! but just showing that this works for string types, but not for `let` above
echo "${ar[$idbad1]}"
ar["$idbad2"]+=33 #works but it's string as expected; but set -x doesn't show value of $idbad2 when displaying: + ar["$idbad2"]+=33
echo "${ar[$idbad2]}"
echo "${ar["["]}"
echo "before0: ${ar[$idbad1]}"
((ar['$idbad1']++)) #works but not as you'd expect(ie. it evaluates $idbad1); set -x shows: + (( ar[$idbad1]++ ))
echo "after0: ${ar[$idbad1]}"
((ar['$idbad2']++)) #works, workaround
#echo "before1: ${ar[$idbad1]}"
((ar[$idbad1]++)) #works as expected! set -x shows: + (( ar[bad string]++ ))
#echo "after1: ${ar[$idbad1]}"
((ar[$idbad2]++)) #fails: ((: ar[[]++: bad array subscript (error token is "ar[[]++")
#echo "before2: ${ar[$idbad1]}"
((ar["$idbad1"]++)) #works as expected!
#echo "after2: ${ar[$idbad1]}"
((ar["$idbad2"]++)) #fails: ((: ar[[]++: bad array subscript (error token is "ar[[]++")
