Convert text file into a comma delimited string

Question

I don\'t seem to locate an SO question that matches this exact problem.

I have a text file that has one text token per line, without any commas, tabs, or quotes. I want

Answer 1

Tested the four approaches on a Linux box - Bash only, paste, awk, Perl, as well as the tr | sed approach shown in the question:

#!/bin/bash

# generate test data
seq 1 10000 > test.file

times=${1:-50}

printf '%s\n' "Testing paste solution"
time {
    for ((i=0; i < times; i++)); do
      csv_string=$(paste -sd, test.file)
    done
}

printf -- '----\n%s\n' "Testing pure Bash solution"
time {
    for ((i=0; i < times; i++)); do
      csv_string=$(

Surprisingly, the Bash only solution does quite poorly. paste comes on top, followed by tr | sed, Awk, and perl:

Testing paste solution

real    0m0.109s
user    0m0.052s
sys 0m0.075s
----
Testing pure Bash solution

real    1m57.777s
user    1m57.113s
sys 0m0.341s
----
Testing Awk solution

real    0m0.221s
user    0m0.152s
sys 0m0.077s
----
Testing Perl solution

real    0m0.424s
user    0m0.388s
sys 0m0.080s
----
Testing tr | sed solution

real    0m0.162s
user    0m0.092s
sys 0m0.141s

For some reasons, csv_string=${csv_string//$'\n'/,} hangs on macOS Mojave running Bash 4.4.23.

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