#!/bin/bash
s="05-620 Karpacz"
sed 's/^[0-9]\{2\}[ -][0-9]\{3\}[[:space:]][0-9A-Za-z]\{1,\}/50-370 Wroclaw/' <<< "$s"
sed 's/^[0-9]\{2\}[ -][0-9]\{3\}[[:space:]][[:alnum:]]\+/50-370 Wroclaw/' <<< "$s"
sed -E 's/^[0-9]{2}[ -][0-9]{3}[[:space:]]+[[:alnum:]]+/50-370 Wroclaw/' <<< "$s"
IyEvYmluL2Jhc2gKcz0iMDUtNjIwIEthcnBhY3oiCnNlZCAncy9eWzAtOV1cezJcfVsgLV1bMC05XVx7M1x9W1s6c3BhY2U6XV1bMC05QS1aYS16XVx7MSxcfS81MC0zNzAgV3JvY2xhdy8nIDw8PCAiJHMiCnNlZCAncy9eWzAtOV1cezJcfVsgLV1bMC05XVx7M1x9W1s6c3BhY2U6XV1bWzphbG51bTpdXVwrLzUwLTM3MCBXcm9jbGF3LycgPDw8ICIkcyIKc2VkIC1FICdzL15bMC05XXsyfVsgLV1bMC05XXszfVtbOnNwYWNlOl1dK1tbOmFsbnVtOl1dKy81MC0zNzAgV3JvY2xhdy8nIDw8PCAiJHMi