About
A sequence expression is a construct that creates sequence of numbers or characters.
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Syntax
It's a brace expansion and takes the form
{x..y}
where x and y are either:
A correctly-formed brace expansion must contain:
- unquoted opening
- closing braces,
- and at least one unquoted comma or a valid sequence expression.
Any incorrectly formed brace expansion is left unchanged.
A { or , may be quoted with a backslash to prevent its being considered part of a brace expression.
To avoid conflicts with parameter expansion, the string ${ is not considered eligible for brace expansion.
Management
Creation
Integers
When integers are supplied, the expression expands to each number between x and y, inclusive.
echo {1..10}
1 2 3 4 5 6 7 8 9 10
Character
When characters are supplied, the expression expands to each character lexicographically between x and y, inclusive. Note that both x and y must be of the same type.
echo {a..f}
a b c d e f
Loop
Integer For
- With hard-coded limit
for i in {1..10};
do
echo $i;
done
# or
for (( n=1; n<=10; n++ ))
do
echo "$n"
done
- With variable limit
end=10
for i in $(seq 1 $end);
do
echo $i;
done
Integer While
count=0
while [ $count -le 10 ]
do
echo "$count"
count=$(( $count + 1 ))
done
Character For
for letter in {a..f}
do
echo "$letter"
done
- A array
for color in Blue Red
do
echo "$color"
done