-a filenum output all lines
| -v filenum reverse, i.e. suppress joined output lines
| -e EMPTY replace missing input fields with EMPTY
| -i
--ignore-case ignore case
| -o format format for output line
| -t char char is input and output field separator
| -1 field join on this field of file 1
| -2 field join on this .field of file 2
| -j field equivalent to '-1 FIELD -2 FIELD'
| --check-order inputs are correctly sorted
| --nocheck-order do not check that the input is correctly sorted
| --header first line in each file is field header,
always output them .
| -z
--zero-terminated end lines with 0 byte, not newline
| --help
join --help
Usage: join [OPTION]... FILE1 FILE2
For each pair of input lines with identical join fields, write a line to standard output.
The default join field is the first, delimited by whitespace.
When FILE1 or FILE2 (not both) is -, read standard input.
-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
--help display this help and exit
--version output version information and exit
| --version output version information and exit
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