mirror of https://github.com/n-hys/bash.git
42 lines
1.5 KiB
Plaintext
42 lines
1.5 KiB
Plaintext
# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# this captures how bash and ksh93 expand indexed array subscripts in
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# various contexts. if changes are ever made, or an option added to do
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# this differently, the diffs will show up here
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typeset -a array
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index='$( echo >&2 foo )' # Literal shell code should never be evaluated unless an 'eval' is involved.
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echo ${array[ $index ]} # [] expands $index, results in a literal that [] does not re-evaluate.
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echo $(( $index )) # (( )) expands $index, results in a literal that (( )) does not re-evaluate.
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echo $(( array[ $index ] )) # (( )) expands $index, results in a literal that [] DOES re-evaluate.
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(( array[ $index ] ))
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typeset -a a
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: $(( a[$index]=5 ))
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#shopt -s assoc_expand_once
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echo $((1+a[$index]))
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echo $((1+a[\$index]))
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echo "1+${a[$index]}"
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# intermediate problems discovered while bash-5.0 was in testing
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a=0
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echo $(( a[a[0]] ))
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echo ${a[a[a[0]]]}
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echo $(( a[a[a[0]]] ))
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