How to split a list by comma not space - linux

Question

I want to split a text with comma , not space in for foo in list. Suppose I have a CSV file CSV_File with following text inside it:
Hello,World,Questions,Answers,bash shell,script
...
I used following code to split it into several words:
for word in $(cat CSV_File | sed -n 1'p' | tr ',' '\n')
do echo $word
done
It prints:
Hello
World
Questions
Answers
bash
shell
script
But I want it to split the text by commas not spaces:
Hello
World
Questions
Answers
bash shell
script
How can I achieve this in bash?

Answer 1

Set IFS to ,:
sorin#sorin:~$ IFS=',' ;for i in `echo "Hello,World,Questions,Answers,bash shell,script"`; do echo $i; done
Hello
World
Questions
Answers
bash shell
script
sorin#sorin:~$

Answer 2

Using a subshell substitution to parse the words undoes all the work you are doing to put spaces together.
Try instead:
cat CSV_file | sed -n 1'p' | tr ',' '\n' | while read word; do
echo $word
done
That also increases parallelism. Using a subshell as in your question forces the entire subshell process to finish before you can start iterating over the answers. Piping to a subshell (as in my answer) lets them work in parallel. This matters only if you have many lines in the file, of course.

Answer 3

I think the canonical method is:
while IFS=, read field1 field2 field3 field4 field5 field6; do
do stuff
done < CSV.file
If you don't know or don't care about how many fields there are:
IFS=,
while read line; do
# split into an array
field=( $line )
for word in "${field[#]}"; do echo "$word"; done
# or use the positional parameters
set -- $line
for word in "$#"; do echo "$word"; done
done < CSV.file

Answer 4

kent$ echo "Hello,World,Questions,Answers,bash shell,script"|awk -F, '{for (i=1;i<=NF;i++)print $i}'
Hello
World
Questions
Answers
bash shell
script

Answer 5

Create a bash function
split_on_commas() {
local IFS=,
local WORD_LIST=($1)
for word in "${WORD_LIST[#]}"; do
echo "$word"
done
}
split_on_commas "this,is a,list" | while read item; do
# Custom logic goes here
echo Item: ${item}
done
... this generates the following output:
Item: this
Item: is a
Item: list
(Note, this answer has been updated according to some feedback)

Answer 6

Read: http://linuxmanpages.com/man1/sh.1.php
& http://www.gnu.org/s/hello/manual/autoconf/Special-Shell-Variables.html
IFS The Internal Field Separator that is used for word splitting
after expansion and to split lines into words with the read
builtin command. The default value is ``''.
IFS is a shell environment variable so it will remain unchanged within the context of your Shell script but not otherwise, unless you EXPORT it. ALSO BE AWARE, that IFS will not likely be inherited from your Environment at all: see this gnu post for the reasons and more info on IFS.
You're code written like this:
IFS=","
for word in $(cat tmptest | sed -n 1'p' | tr ',' '\n'); do echo $word; done;
should work, I tested it on command line.
sh-3.2#IFS=","
sh-3.2#for word in $(cat tmptest | sed -n 1'p' | tr ',' '\n'); do echo $word; done;
World
Questions
Answers
bash shell
script

Answer 7

You can use:
cat f.csv | sed 's/,/ /g' | awk '{print $1 " / " $4}'
or
echo "Hello,World,Questions,Answers,bash shell,script" | sed 's/,/ /g' | awk '{print $1 " / " $4}'
This is the part that replace comma with space
sed 's/,/ /g'

Answer 8

For me, use array split is simpler ref
IN="bla#some.com;john#home.com"
arrIN=(${IN//;/ })
echo ${arrIN[1]}

Answer 9

Using readarray(mapfile):
$ cat csf
Hello,World,Questions,Answers,bash shell,script
$ readarray -td, arr < csf
$ printf '%s\n' "${arr[#]}"
Hello
World
Questions
Answers
bash shell
script