grep or awk : Match on alpha prefixed number range

Question

How would one match on a range of system names that are prefixed by letters?

Given: sfc30700 through sfc30900

Want all systems listed in file from sfc30750 to sfc30850 for example, and the sequence not fully populated.

I did attempt to use egrep like so, however it returns an error.

cat mahinelist.txt | egrep ':[[:sfc:]]\{30750,30850\}:'
egrep: Invalid character class name

Answer 1

This prints out all lines containing " sfc " directly followed by a number between " 30750 " and " 30850 ".

$ cat file
sfcdd30784
sfc30689
word sfc30750 word
sfc30753
sfc30756
sfc30900
sfc30901
daw30900

$ awk '{ n=match($0,"sfc"); m=substr($0,n+3,5)*1;
    if(m>=30750 && m<=30850){ print } }' file
word sfc30750 word
sfc30753
sfc30756