I want to add the elements of the fourth column in each line of the file to an array, but now I don't know how to add the separated elements to another array. My approach seems to have some problems:
#!/bin/bash
declare -a arr
cat 2.csv | while read line
do
IFS=',' read -ra str <<< "$line"
# echo ${str[3]}
arr+=(${str[3]})
done
for(( i=0;i<${#arr[@]};i++)) do
echo ${arr[i]};
done;
The problem is that each process in a pipeline operates inside a subshell. Thus, this code modifies arr inside a subshell. No change to the environment survives outside the subshell.
cat 2.csv | while read line
do
IFS=',' read -ra str <<< "$line"
# echo ${str[3]}
arr+=(${str[3]})
done
To avoid that, use redirection:
while read line
do
IFS=',' read -ra str <<< "$line"
# echo ${str[3]}
arr+=(${str[3]})
done <2.csv
In addition to John1024's answer, there's no need to read the line, and the read it again to split it. You can do the splitting the first time:
while IFS=, read -ra str
do
arr+=("${str[3]}") # Quote here if you don't want further splitting
done < 2.csc
Instead of reading into an a array, you could read into variables and throw away those you don't need:
while IFS=, read -r _ _ _ str _; do arr+=("$str"); done < 2.csv
This is only practical if the index you want is relatively low, though.
Another option, using cut and process substitution:
readarray -t arr < <(cut -d, -f4 2.csv)