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join

join lines of two files on a common field

References

  • man join

Synopsis

join [OPTION]... FILE1 FILE2

Options

  • -a FILENUM also print unpairable lines from file FILENUM, where FILENUM is 1 or 2, corresponding to FILE1 or FILE2
  • -e EMPTY replace missing input fields with EMPTY
  • -i, --ignore-case ignore differences in case when comparing fields
  • -j FIELD equivalent to '-1 FIELD -2 FIELD'
  • -o FORMAT obey FORMAT while constructing output line
  • -t CHAR use CHAR as input and output field separator
  • -v FILENUM like -a FILENUM, but suppress joined output lines
  • -1 FIELD join on this FIELD of file 1
  • -2 FIELD join on this FIELD of file 2
  • --check-order check that the input is correctly sorted, even if all input lines are pairable
  • --nocheck-order do not check that the input is correctly sorted
  • --header treat the first line in each file as field headers, print them without trying to pair them
  • -z, --zero-terminated end lines with 0 byte, not newline

Usage

Reference : https://shapeshed.com/unix-join/

Default

Sample 1

$ cat foodtypes
1 Protein
2 Carbohydrate
3 Fat

$ cat foods
1 Cheese
2 Potato
3 Butter

Join

$ join foodtypes foods
1 Protein Cheese
2 Carbohydrate Potato
3 Fat Butter

Join by Sepcified Fields

Sample 2

$ cat wine
Red Beaunes France
White Reisling Germany
Red Riocha Spain

$ cat reviews
Beaunes Great!
Reisling Terrible!
Riocha Meh

Joined by Sepcified fields

$ join -1 2 -2 1 wine reviews
Beaunes Red France Great!
Reisling White Germany Terrible!
Riocha Red Spain Meh

Sort Before Joining

Sample 3

$ cat wine
White Reisling Germany
Red Riocha Spain
Red Beaunes France

$ cat reviews
Riocha Meh
Beaunes Great!
Reisling Terrible!

Wrong

$ join -1 2 -2 1 wine reviews
join: wine:3: is not sorted: Red Beaunes France
join: reviews:2: is not sorted: Beaunes Great!
Riocha Red Spain Meh
Beaunes Red France Great!

Correct

$ join -1 2 -2 1 <(sort -k 2 wine) <(sort reviews)
Beaunes Red France Great!
Reisling White Germany Terrible!
Riocha Red Spain Meh

Sepcify Separator

Sample 4

  • An example is a CSV file where the separator is ,.
$ cat names.csv
1,John Smith,London
2,Arthur Dent, Newcastle
3,Sophie Smith,London

$ cat transactions.csv
£1234,Deposit,John Smith
£4534,Withdrawal,Arthur Dent
£4675,Deposit,Sophie Smith

Specify Separator

$ join -1 2 -2 3 -t , names.csv transactions.csv
John Smith,1,London,£1234,Deposit
Arthur Dent,2, Newcastle,£4534,Withdrawal
Sophie Smith,3,London,£4675,Deposit

Output Format

Use Sample 4 above

$ join -1 2 -2 3 -t , -o 1.1,1.2,1.3,2.2,2.1 names.csv transactions.csv
1,John Smith,London,Deposit,£1234
2,Arthur Dent, Newcastle,Withdrawal,£4534
3,Sophie Smith,London,Deposit,£4675