21.15. Making Text in Columns with pr
The pr command (Section 45.6) is famous for printing a file neatly on a page -- with margins at top and bottom, filename, date, and page numbers. It can also print text in columns: one file per column or many columns for each file.
The -t option takes away the heading and margins at the top and bottom of each page. That's useful when "pasting" data into columns with no interruptions.
21.15.1. One File per Column: -m
% pr -m -t file1 file2 file3 The lines The lines The lines of file1 of file2 of file3 are here are here are here ... ... ...
pr may use TAB characters between columns. If that would be bad, you can pipe pr's output through expand. Many versions of pr have a -sX option that sets the column separator to the single character X.
By default, pr -m doesn't put filenames in the heading. If you want that, use the -h option to make your own heading. Or maybe you'd like to make a more descriptive heading. Here's an example using process substitution to compare a directory with its RCS (Section 39.5) subdirectory:
% pr -m -h "working directory compared to RCS directory" <(ls) <(ls RCS) 2000-11-22 23:57 working directory compared to RCS directory Page 1 0001.sgm 0001.sgm,v 0002.sgm 0002.sgm,v 0007.sgm 0007.sgm,v 0008.sgm 0008.sgm,v ...
(The heading comes from the GNU version of pr. Later examples in this article use a different version with a different heading format.)
21.15.2. One File, Several Columns: -number
An option that's a number will print a file in that number of columns. For instance, the -3 option prints a file in three columns. The file is read, line by line, until the first column is full (by default, that takes 56 lines). Next, the second column is filled. Then, the third column is filled. If there's more of the file, the first column of page 2 is filled -- and the cycle repeats:
% pr -3 file1 Nov 1 19:44 1992 file1 Page 1 Line 1 here Line 57 here Line 115 here Line 2 here Line 58 here Line 116 here Line 3 here Line 59 here Line 117 here ... ... ...
The columns aren't balanced -- if the file will fit into one column, the other columns aren't used. You can change that by adjusting -l, the page length option; see the section below.
21.15.3. Order Lines Across Columns: -l
% pr -l1 -t -3 file1 Line 1 here Line 2 here Line 3 here Line 4 here Line 5 here Line 6 here Line 7 here Line 8 here Line 9 here ... ... ...
Use the -l1 (page length 1 line) and -t (no title) options. Each "page" will be filled by three lines (or however many columns you set). You have to use -t; otherwise, pr will silently ignore any page lengths that don't leave room for the header and footer. That's just what you want if you want data in columns with no headings.
If you want headings too, pipe the output of pr through another pr:
% pr -l1 -t -3 file1 | pr -h file1 Nov 1 19:48 1992 file1 Page 1 Line 1 here Line 2 here Line 3 here Line 4 here Line 5 here Line 6 here Line 7 here Line 8 here Line 9 here ... ... ...
The -h file1 puts the filename into the heading.
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