coreutils: join invocation

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1 8.3 ‘join’: Join lines on a common field
1 ========================================
1 
1 ‘join’ writes to standard output a line for each pair of input lines
1 that have identical join fields.  Synopsis:
1 
1      join [OPTION]... FILE1 FILE2
1 
1    Either FILE1 or FILE2 (but not both) can be ‘-’, meaning standard
1 input.  FILE1 and FILE2 should be sorted on the join fields.
1 
1      $ cat file1
1      a 1
1      b 2
1      e 5
1 
1      $ cat file2
1      a X
1      e Y
1      f Z
1 
1      $ join file1 file2
1      a 1 X
1      e 5 Y
1 
1 ‘join’’s default behavior (when no options are given):
1    • the join field is the first field in each line;
1    • fields in the input are separated by one or more blanks, with
1      leading blanks on the line ignored;
1    • fields in the output are separated by a space;
1    • each output line consists of the join field, the remaining fields
1      from FILE1, then the remaining fields from FILE2.
1 

Menu

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· General options in join      Options which affect general program behavior.
· Sorting files for join       Using ‘sort’ before ‘join’.
· Working with fields          Joining on different fields.
· Paired and unpaired lines    Controlling ‘join’’s field matching.
· Header lines                 Working with header lines in files.
· Set operations               Union, Intersection and Difference of files.
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