Merge two zsh history files

merge-zsh-history.sh

#!/bin/bash
# Inspired on https://david-kerwick.github.io/2017-01-04-combining-zsh-history-files/
set -e
history1=$1
history2=$2
merged=$3

echo "Merging history files: $history1 + $history2"

test ! -f $history1 && echo "File $history1 not found" && exit 1
test ! -f $history2 && echo "File $history2 not found" && exit 1

cat $history1 $history2 | awk -v date="WILL_NOT_APPEAR$(date +"%s")" '{if (sub(/\\$/,date)) printf "%s", $0; else print $0}' | LC_ALL=C sort -u | awk -v date="WILL_NOT_APPEAR$(date +"%s")" '{gsub('date',"\\\n"); print $0}' > $merged

echo "Merged to: $merged"

I tried the builtin fc method mentioned above but it doesn't sort the output! So in the resulting history you get all of one file first then all of the other file. Apparently zsh doesn't care that the timestamps are out of order and doesn't sort them. But the awk solution worked great for me!

Thanks, I was getting error with merge_history.sh:
awk: towc: multibyte conversion failure on: '�`|:"' ()[]{}<>\t"'

builtin worked like a charm. Thanks

Thank you!