CODEWITHSUNDEEP
arraysbash
Baldrick
Baldrick

Reputation: 11002

Read tab-separated file line into array

I would like to read a file into a script, line by line. Each line in the file is multiple values separated by a tab, I'd like to read each line into an array.

Typical bash "read file by line" example;

while read line
do
echo $line;
done < "myfile"

For me though, myfile looks like this (tab separated values);

value1 value2 value3
value4 value5 value6

On each iteration of the loop, I'd like each line to go into an array so I can

while read line into myArray
do
 echo myArray[0]
 echo myArray[1]
 echo myArray[2]
done < "myfile"

This would print the following on the first loop iteration;

value1
value2
value3

Then on the second iteration it would print

value4
value5
value6

Is this possible? The only way I can see is to write a small function to break out the values manually, is there built in support in bash for this?

Upvotes: 88

Views: 153902

Answers (3)

slylittl3
slylittl3

Reputation: 291

If you really want to put the values in an array, then @ruakh's answer is the correct approach. But read also supports putting each value in a separate variable, which is more readable if you have meaningful names you can use for them. For example, if the three columns are user-ID, username, and e-mail address, then you might write:

while IFS=$'\t' read -r user_id username email ; do
  echo "${user_id}"
  echo "${username}"
  echo "${email}"
done < "myfile"

Upvotes: 27

Dinuksha Samanage
Dinuksha Samanage

Reputation: 11

You could also try,

OIFS=$IFS;
IFS="\t";

animals=`cat animals.txt`
animalArray=$animals;

for animal in $animalArray
do
    echo $animal
done

IFS=$OIFS;

Upvotes: 1

ruakh
ruakh

Reputation: 183241

You're very close:

while IFS=$'\t' read -r -a myArray
do
 echo "${myArray[0]}"
 echo "${myArray[1]}"
 echo "${myArray[2]}"
done < myfile

(The -r tells read that \ isn't special in the input data; the -a myArray tells it to split the input-line into words and store the results in myArray; and the IFS=$'\t' tells it to use only tabs to split words, instead of the regular Bash default of also allowing spaces to split words as well. Note that this approach will treat one or more tabs as the delimiter, so if any field is blank, later fields will be "shifted" into earlier positions in the array. Is that O.K.?)

Upvotes: 198

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