Shell Programming and Scripting

Sort Key Definition Using the -k Flag

       The -k KeyDefinition flag uses the following form:

       -k [ FStart [ .CStart ] ] [ Modifier ] [ , [ FEnd [ .CEnd ] ][ Modifier ] ]

       The sort key includes all characters beginning with the field specified by the FStart variable and the column specified by the CStart variable and ending with the field
       specified by the FEnd variable and the column specified by the CEnd variable. If Fend is not specified, the last character of the line is assumed. If CEnd is not specified
       the last character in the FEnd field is assumed. Any field or column number in the KeyDefinition variable may be omitted. The default values are:
       FStart
            Beginning of the line
       CStart
            First column in the field
       FEnd
            End of the line
       CEnd
            Last column of the field

       If there is any spaces between the fields, sort considers them as separate fields.

       The value of the Modifier variable can be one or more of the letters b, d, f, i, n, or r. The modifiers apply only to the field definition they are attached to and have the

       same effect as the flag of the same letter. The modifier letter b applies only to the end of the field definition to which it is attached.
For example:

       -k 3.2b,3r

       specifies a sort key beginning in the second nonblank column of the third field and extending to the end of the third field, with the sort on this key to be done in reverse
       collation order. If the FStart variable and the CStart variable fall beyond the end of the line or after the FEnd variable and the CEnd variable, then the sort key is
       ignored.