Info Catalog coreutils: Paired and unpaired lines coreutils: join invocation coreutils: Set operations

coreutils: Header lines

 
 8.3.5 Header lines
 ------------------
 
 The ‘--header’ option can be used when the files to join have a header
 line which is not sorted:
 
      $ cat file1
      Name     Age
      Alice    25
      Charlie  34
 
      $ cat file2
      Name   Country
      Alice  France
      Bob    Spain
 
      $ join --header -o auto -e NA -a1 -a2 file1 file2
      Name     Age   Country
      Alice    25    France
      Bob      NA    Spain
      Charlie  34    NA
 
    To sort a file with a header line, use GNU ‘sed -u’.  The following
 example sort the files but keeps the first line of each file in place:
 
      $ ( sed -u 1q ; sort -k2b,2 ) < file1 > file1.sorted
      $ ( sed -u 1q ; sort -k2b,2 ) < file2 > file2.sorted
      $ join --header -o auto -e NA -a1 -a2 file1.sorted file2.sorted > file3
 

Info Catalog coreutils: Paired and unpaired lines coreutils: join invocation coreutils: Set operations