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You can assign multiple values to multiple variables by separating variables and values with commas , . You can assign to more than three variables. It is also possible to assign to different types. If there is one variable on the left side, it is assigned as a tuple.
A variable in bash can contain a number, a character, a string of characters. You have no need to declare a variable, just assigning a value to its reference will create it.
A command with the << operator will do the following things : Launch the program specified in the left of the operator, cat for instance. Grab user input, including newlines, until what is specified on the right of the operator is met on one line, EOF for instance.
First thing that comes into my mind:
read -r a b c <<<$(echo 1 2 3) ; echo "$a|$b|$c"
output is, unsurprisingly
1|2|3
I wanted to assign the values to an array. So, extending Michael Krelin's approach, I did:
read a[{1..3}] <<< $(echo 2 4 6); echo "${a[1]}|${a[2]}|${a[3]}"
which yields:
2|4|6
as expected.
I think this might help...
In order to break down user inputted dates (mm/dd/yyyy) in my scripts, I store the day, month, and year into an array, and then put the values into separate variables as follows:
DATE_ARRAY=(`echo $2 | sed -e 's/\// /g'`)
MONTH=(`echo ${DATE_ARRAY[0]}`)
DAY=(`echo ${DATE_ARRAY[1]}`)
YEAR=(`echo ${DATE_ARRAY[2]}`)
Sometimes you have to do something funky. Let's say you want to read from a command (the date example by SDGuero for example) but you want to avoid multiple forks.
read month day year << DATE_COMMAND
$(date "+%m %d %Y")
DATE_COMMAND
echo $month $day $year
You could also pipe into the read command, but then you'd have to use the variables within a subshell:
day=n/a; month=n/a; year=n/a
date "+%d %m %Y" | { read day month year ; echo $day $month $year; }
echo $day $month $year
results in...
13 08 2013
n/a n/a n/a
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