How can I count most occuring sequence of 3 letters within a word with a bash script

Question

I have a sample file like

XYZAcc
ABCAccounting
Accounting firm
Accounting Aco
Accounting Acompany
Acoustical consultant

Here I need to grep

Answer 1

Here's how to get started with what I THINK you're trying to do:

$ cat tst.awk
BEGIN { stringLgth = 3 }
{
    for (fldNr=1; fldNr<=NF; fldNr++) {
        field = $fldNr
        fieldLgth = length(field)
        if ( fieldLgth >= stringLgth ) {
            maxBegPos = fieldLgth - (stringLgth - 1)
            for (begPos=1; begPos<=maxBegPos; begPos++) {
                string = tolower(substr(field,begPos,stringLgth))
                cnt[string]++
            }
        }
    }
}
END {
    for (string in cnt) {
        print string, cnt[string]
    }
}

.

$ awk -f tst.awk file | sort -k2,2nr
acc 5
cou 5
cco 4
ing 4
nti 4
oun 4
tin 4
unt 4
aco 3
abc 1
ant 1
any 1
bca 1
cac 1
cal 1
com 1
con 1
fir 1
ica 1
irm 1
lta 1
mpa 1
nsu 1
omp 1
ons 1
ous 1
pan 1
sti 1
sul 1
tan 1
tic 1
ult 1
ust 1
xyz 1
yza 1
zac 1