mirror of https://github.com/n-hys/bash.git
92 lines
1.9 KiB
Plaintext
92 lines
1.9 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 shows the expansions an array subscript undergoes before being run
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# through the arithmetic evaluator
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b=(0 1 2 3)
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# array subscripts undergo variable expansion
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a=2
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echo ${b[$a]}
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# array subscripts undergo command substitution
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echo ${b[$(echo 2)]}
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c='1+1'
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d='1-+1'
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# array subscripts are expanded and the expanded value is treated as an
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# expression
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echo ${b[$c]}
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echo ${b[c]}
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echo ${b[$d]}
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echo ${b[d]}
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# array subscripts undergo parameter expansion
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set -- 1 2 3
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echo ${b[$1]}
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# array subscripts undergo tilde expansion
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HOME=2
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echo ${b[~]}
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# array subscripts undergo word splitting -- bug in bash versions through 4.3
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x='b[$d]'
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IFS=-
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echo $((x))
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IFS=$' \t\n'
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set -- 1 + 2
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x='d'
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IFS=-
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echo $((x))
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IFS=$' \t\n'
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# start of quoting tests; make sure that subscript is treated as double
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# quoted (inhibits word splitting) but that double quotes are silently
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# discarded through quote removal
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echo $(( $@ ))
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echo "$(( $@ ))"
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echo $(( "$x" ))
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echo $(( "x" ))
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unset a foo bar
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a=(zero one two three four five six seven eight nine ten)
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echo ${a[0]}
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echo ${a["0"]}
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foo=1
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echo ${a[$foo]}
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echo ${a["$foo"]}
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echo ${a[foo]}
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echo ${a["foo"]}
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bar=2
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echo ${a[" $bar "]}
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echo ${a[" bar "]}
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# tilde expansion is performed by array subscript expansion but not by posix
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# style arithmetic expansion
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HOME=2
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echo $(( ~ ))
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