# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(\[cid:(?:[0-9A-Z-]{7,8}){5}\])//g;t' <<< "[cid:B54FD59F-8DE7-4ED1-A0C7-19E52F83A8D7]
[cid:
B54FD59F-8DE7-4ED1-A0C7-19E52F83A8D7]
[pid:B54FD59F-8DE7-4ED1-A0C7-19E52F83A8D7]
[cid:B54FD59F-8DE7-4ED1-A0C7-19E52F83A8D7]
[cid:B54FD]
[cid:B54FD59F-8DE7-4ED1-A0CU]-[3A8D7]-[19E52F83A8D7]
// lowercase won't match unless you include /i
[cid:2992S39a-1111-EEEE-9999-1239992EEIUE]"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html