When I execute ls /directory | grep '[^term]' in Bash I get a regular listing, as if the grep command is ignored somehow. I tried the same thing with egrep, I tried to use it with double and single quotes, but to no better results. When I try ls /directory | grep '^[term] I get all entries beginning with term – as expected.
My computer is running macOS 10.12.3 and I am using the system-installed grep utility with version 2.5.1-FreeBSD.
Is there a historical reason why Bash “globbing” and regular expressions are not identical? For example, I believe that in Bash [1-2]* matches anything that starts with a 1 or a 2 followed by anything else, while as a regular expression [1-2]* would match only a sequence of 1s and 2s. My Bash scripting and REGEX foo are both pretty weak and I regularly run into problems associated with these differences which made me curious was to why they are different.
I have a text file named abd shown below.