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Bash - reverse variable
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In this article, we would like to show you how to reverse variable passed from command line using Bash.
To reverse the string we use:
#operator - to get string length,forloop - to iterate the string backwards, constructing thereversedstring by adding characters one by one from the end to the start.
Example ./script.sh file:
xxxxxxxxxx1
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variable="123"4
reversed=""5
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for ((i=${#variable}-1; i>=0; --i))7
do8
reversed="$reversed${variable:$i:1}"9
done10
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echo "variable: $variable reversed: $reversed"Run in command line:
xxxxxxxxxx1
./script.shOutput:
xxxxxxxxxx1
variable: 123 result: 321Example ./script.sh file:
xxxxxxxxxx1
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variable="$1"4
reversed=""5
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for ((i=${#variable}-1; i>=0; --i))7
do8
reversed="$reversed${variable:$i:1}"9
done10
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echo "$reversed"Run in command line:
xxxxxxxxxx1
./script.sh "Example text..."Output:
xxxxxxxxxx1
...txet elpmaxE
xxxxxxxxxx1
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function reverse_string() {4
local string="$1"5
local result=""6
for ((i=${#string}-1; i>=0; --i))7
do8
result="$result${string:$i:1}"9
done10
echo "$result";11
}12
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# Usage example 1:15
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reverse_string "123"17
reverse_string "abc"18
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# Usage example 2:21
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string_1="123"23
result_1="$(reverse_string "$string_1")"24
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string_2="abc"26
result_2="$(reverse_string "$string_2")"27
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echo "string: $string_1 result: $result_1"29
echo "string: $string_2 result: $result_2"Output:
xxxxxxxxxx1
3212
cba3
string: 123 result: 3214
string: abc result: cba
