CODEWITHSUNDEEP
linuxbashshellscriptinggrep
Adam
Adam

Reputation: 47

egrep to print lines with one and only one t

I'm attempting to print lines that have only one t, or only one T, where anything else is fine. IE no lines that have no t's, no lines with 2 or more t's, and no lines that have 1 T and 1 t.

I'm trying :

egrep '[tT]{1,1}$' filename

and this is showing the following lines:

     nopqrstuvwxyz
     letters    (this line is the one that should not be here)
 The price is *$2*
      one two three (this line should not be here either)
    ONE TWO
 THREE

These are all the lines that have a t or T in them in the file. How should I be going about this?

Upvotes: 1

Views: 62

Answers (2)

stack0114106
stack0114106

Reputation: 8721

If you are considering Perl, below would work

> cat ip.txt
foobaz
nopqrstuvwxyz
letters
The price is *$2*
one two three
ONE TWO
THREE
1234
> perl -ne ' $x++ for(/t/ig);print if $x==1 ; $x=0 ' ip.txt
nopqrstuvwxyz
The price is *$2*
ONE TWO
THREE
>

If you need to grep with exact 2 matches - just change the condition to $x==2.

Upvotes: 0

Sundeep
Sundeep

Reputation: 23677

$ cat ip.txt
foobaz
nopqrstuvwxyz
letters
The price is *$2*
one two three
ONE TWO
THREE
1234

$ grep -ix '[^t]*t[^t]*' ip.txt
nopqrstuvwxyz
The price is *$2*
ONE TWO
THREE
  • -i to ignore case
  • -x to match whole line only
    • by default, grep matches anywhere in the line
    • without -x, you'd need grep -i '^[^t]*t[^t]*$'
  • [^t]* any character other than t (because of -i option, T would also be not matched)


You can also use awk here:

$ awk -F'[tT]' 'NF==2' ip.txt
nopqrstuvwxyz
The price is *$2*
ONE TWO
THREE
  • -F'[tT]' specify t or T as field separator
  • NF==2 print if line contains two fields, i.e if the line had one t or T

Upvotes: 3

Related Questions