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col -- Command Remove reverse and half-line motions col [ -bdfx ][ -pn ] The command col reads the standard input and writes to the standard output. It removes reverse and half-line motions from the output of nroff for the benefit of output devices that cannot perform them. It maintains an image of the page in memory and performs these motions virtually so they do not appear on the output. col understands four escape sequences: <esc> 7 for reverse line feed, <esc> 8 for half reverse line feed, <esc> 9 for half forward line feed, and <esc> B for a forward line feed. It removes <esc> (ASCII 033) from the input stream if it is followed by any other character. Eight control characters besides <esc> are interpreted by col. Newline, return, space, backspace, and tab carry their usual meaning. VT (013) is an alternate form of reverse line feed. The characters SO (017) and SI (016) signal the start and end of text in an alternate character set. col remembers the character set for each character and uses SO and SI to distinguish them on the output. col removes all other control characters from the input stream. col recognizes the following options: -b The output device cannot backspace. Only the last of a set of characters destined for a given position will appear. -d Double-space the output. This doubles the length of a document but preserves relative vertical spacing. The -f option has precedence. -f The output device can perform half-forward line feeds. Full lines appear single spaced with half lines between them. This is the only situation in which half forward line feeds appear in the output of col -- reverse line motions never appear. -x Suppress the default conversion of white space to tabs on output. -p n Set the internal page buffer size to n full lines (default, 128). If neither -f nor -d is chosen, col moves non-empty half lines to the next lower full line and pushes all later lines down one line. This can distort the appearance of the document. See Also ASCII, commands, nroff Notes Backing up past the start of a document or of the page buffer loses characters.