Joins the data fields of two files.
join [ -a FileNumber | -v FileNumber ] [ -e String ] [ -o List ] [ -t Character ] [ -1 Field ] [ -2 Field ] File1 File2
The join command reads the files specified by the File1 and File2 parameters, joins lines in the files according to the flags, and writes the results to standard output. The File1 and File2 parameters must be text files. Both File1 and File2 must be sorted in the collating sequence of sort -b on the field that they are being joined by before invoking the join command.
One line appears in the output for each identical join field appearing in both files. The join field is the field in the input files examined by the join command to determine what will be included in the output. The output line consists of the join field, the rest of the line from the file specified by the File1 parameter, and the rest of the line from the file specified by the File2 parameter. Specify standard input in place of either the File1 or File2 parameter by substituting a - (dash) as the file name. Both input files cannot be specified with a - (dash).
Fields are usually separated by a space, a tab character, or a new-line character. In this case, the join command treats consecutive separators as one and discards leading separators.
| -1 Field | Joins the two files using the field specified by the Field variable in the File1 input file. The value of the Field variable must be a positive decimal integer. |
| -2 Field | Joins the two files using the field specified by the Field variable in the File2 input file. The value of the Field variable must be a positive decimal integer. |
| -a FileNumber | Produces an output line for each line in the file specified by the FileNumber variable whose join fields do not match any line in the other input file. The output lines are produced in addition to the default output. The value of the FileNumber variable must be either 1 or 2, corresponding to the files specified by the File1 and File2 parameters, respectively. If this flag is specified with the -v flag, this flag is ignored. |
| -e String | Replaces empty output fields with the string specified by the String variable. |
| -o List | Constructs an output line to comprise the fields specified in the List variable. One of the following forms applies to
the List variable:
|
| -t Character | Uses the character specified by the Character parameter as the field separator character in the input and the output. Every appearance of the character in a line is significant. The default separator is a space. With default field separation, the collating sequence is that of the sort -b command. If you specify -t, the sequence is that of a plain sort. To specify a tab character, enclose it in single quotation marks. |
| -v FileNumber | Produces an output line for each line in the file specified by the FileNumber variable whose join fields do not match any line in the other input file. Default output is not produced. The value of the FileNumber variable must be either 1 or 2, corresponding to the files specified by File1 and File2 parameters, respectively. If this flag is specified with the -a flag, the -a flag is ignored. |
This command returns the following exit values:
| 0 | Successful completion. |
| >0 | An error occurred. |
join phonedir names
If the phonedir file contains the following names:
Adams A. 555-6235 Dickerson B. 555-1842 Erwin G. 555-1234 Jackson J. 555-0256 Lewis B. 555-3237 Norwood M. 555-5341 Smartt D. 555-1540 Wright M. 555-1234 Xandy G. 555-5015
and the names file contains these names and department numbers:
Erwin Dept. 389 Frost Dept. 217 Nicholson Dept. 311 Norwood Dept. 454 Wright Dept. 520 Xandy Dept. 999
the join command displays:
Erwin G. 555-1234 Dept. 389 Norwood M. 555-5341 Dept. 454 Wright M. 555-1234 Dept. 520 Xandy G. 555-5015 Dept. 999
Each line consists of the join field (the last name), followed by the rest of the line found in the phonedir file and the rest of the line in the names file.
Erwin G. 555-1234 Dept. 389 Frost Dept. 217 Nicholson Dept. 311 Norwood M. 555-5341 Dept. 454 Wright M. 555-1234 Dept. 520 Xandy G. 555-5015 Dept. 999
This command performs the same join operation as in Example 1, and also lists the lines of names that have no match in the phonedir file. The names Frost and Nicholson are included in the listing, even though they do not have entries in the phonedir file.
| Field 3 of names | Department number |
| Field 1 of names | Last name |
| Field 2 of phonedir | First initial |
| Field 3 of phonedir | Telephone number |
389 Erwin G. 555-1234 454 Norwood M. 555-5341 520 Wright M. 555-1234 999 Xandy G. 555-5015
First, this command sorts the phonedir file by the third field, because both files must be sorted by their join fields. The output of the sort command is then piped to the join command. The - (dash) by itself causes the join command to use this output as its first file. The -1 3 flag defines the third field of the sorted phonedir file as the join field. This is compared to the first field of numbers because its join field is not specified with a -2 flag.
If the numbers file contains:
555-0256 555-1234 555-5555 555-7358
then this command displays the names listed in the phonedir file or each telephone number:
555-0256 Jackson J. 555-1234 Erwin G. 555-1234 Wright M.
Note that the join command lists all the matches for a given field. In this case, the join command lists both Erwin G. and Wright M. as having the telephone number 555-1234. The number 555-5555 is not listed because it does not appear in the phonedir file.
| /usr/bin/join | Contains the join command. |
| /usr/lib/nls/loc/*.src | Contains collation information. |
The awk command, comm command, cut command, paste command, sort command.
Files Overview in AIX 5L Version 5.2 System User's Guide: Operating System and Devices.
Input and Output Redirection Overview in AIX 5L Version 5.2 System User's Guide: Operating System and Devices.
National Language Support Overview for Programming in AIX 5L Version 5.2 National Language Support Guide and Reference.