return common fields in two files

Question

Hi,

I have two files, should compare 1st column of file1 with 1st column of file2 and the resultant file should be file2

For example:

• file1

  apple
  banana
  Mango
  potato
  tomato
  

• file 2

  apple:fruit
  brinjal: vegetable
  lady's finger: vegetable
  orange: fruit
  tomato: vegetable
  potato: vegetable
  

Resultant file should look something like this:

apple:fruit
tomato: vegetable
potato: vegetable

any ideas on this would be appreciated

Thanks

Answer 1

grep "$(cat file1.txt)" file2.txt

Answer 2

In Bash, ksh, zsh:

join -t: <(sort file1) <(sort file2)

In other shells you will need to presort your files.

Answer 3

without the need to sort (less process creation)

$ awk -F":" 'FNR==NR{f[$0];next}($1 in f)' file file2
apple:fruit
tomato: vegetable
potato: vegetable