Assign fields to variables - Bash [duplicate]

Question

Suppose I have a string with pipe separator:

str="1|2|3|4"

I want them to be assigned to specific variables.

var_a=1 var_b=2 var_c=3 var_d=4

I am doing it in this way:

var_a="`echo $str | cut -d'|' -f1`" var_b="`echo $str | cut -d'|' -f2`" var_c="`echo $str | cut -d'|' -f3`" var_d="`echo $str | cut -d'|' -f4`"

Can this be done in an efficient way? Please suggest.

Would it be ok to use an array instead of five different variables? — Socowi
– Socowi, Commented Jul 10, 2018 at 14:18
BTW, echo $str is itself buggy; echo "$str" is slightly better (won't replace a * with a list of filenames, for example); printf '%s\n' "$str" is much better (works correctly with all possible values, including -n or -e, which some versions of echo will consume). See BashPitfalls #14, and the APPLICATION USAGE section of the POSIX echo specification. — Charles Duffy
– Charles Duffy, Commented Jul 10, 2018 at 14:29

anubhava · Accepted Answer · 2018-07-10 14:18:27Z

4

It is better to use an array to store individual delimited values:

str="1|2|3|4" IFS='|' read -ra arr <<< "$str" #examine array values declare -p arr

declare -a arr='([0]="1" [1]="2" [2]="3" [3]="4")'

To loop through array, use:

for i in "${arr[@]}"; do echo "$i"; done

1 2 3 4

answered Jul 10, 2018 at 14:18

anubhava

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3 Comments

Charles Duffy Over a year ago

That's fair assuming the OP really wants to read a completely variable number of items. I'm not sure we know that's the case, vs four specific fields having distinct meanings.

anubhava Over a year ago

Yes, I just suggested an alternative assuming variable number of delimited values in input.

Anshuman Bhoi Over a year ago

Thanks. I'll use array for this purpose.

Charles Duffy · Accepted Answer · 2018-07-10 14:23:10Z

IFS='|' read -r var_a var_b var_c var_d rest <<<"$str"

rest is the variable that gets further columns after the first four, should any others exist. If you just want to discard them, the conventional name to use for a placeholder variable is _.

This is covered in detail in BashFAQ #1: How can I read a file (data stream, variable) line-by-line (and/or field-by-field)?

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