Man Page Formatting, Error Handling, Debugging, Localization, and Files

is not set, manual pages will be formatted with a line length appropriate to the current terminal (using the value of $COLUMNS, and ioctl(2) if available, or falling back to 80 characters if neither is available). Cat pages will only be saved when the default formatting can be used, that is when the termi‐ nal line length is between 66 and 80 characters. MAN_KEEP_FORMATTING Normally, when output is not being directed to a terminal (such as to a file or a pipe), formatting characters are discarded to make it easier to read the result without special tools. However, if $MAN_KEEP_FORMATTING is set to any non‐empty value, these formatting characters are retained. This may be useful for wrappers around man that can interpret formatting characters. MAN_KEEP_STDERR Normally, when output is being directed to a terminal (usually to a pager), any error output from the command used to produce formatted versions of manual pages is discarded to avoid interfering with the pager’s display. Programs such as groff often produce relatively minor error messages about typographical problems such as poor alignment, which are unsightly and generally confusing when displayed along with the manual page. However, some users want to see them anyway, so, if $MAN_KEEP_STDERR is set to any non‐empty value, error output will be displayed as usual. MAN_DISABLE_SECCOMP On Linux, man normally confines subprocesses that handle untrusted data using a seccomp(2) sandbox. This makes it safer to run complex parsing code over arbitrary manual pages. If this goes wrong for some reason unrelated to the content of the page being displayed, you can set $MAN_DISABLE_SECCOMP to any non‐empty value to disable the sandbox. PIPELINE_DEBUG If the $PIPELINE_DEBUG environment variable is set to "1", then man will print debugging messages to standard error describing each subprocess it runs. LANG, LC_MESSAGES Depending on system and implementation, either or both of $LANG and $LC_MESSAGES will be interrogated for the current message locale. man will display its messages in that locale (if available). See setlo‐ cale(3) for precise details. FILES /etc/manpath.config man‐db configuration file. /usr/share/man A global manual page hierarchy. SEE ALSO apropos(1), groff(1), less(1), manpath(1), nroff(1), troff(1), whatis(1), zsoelim(1), manpath(5), man(7), catman(8), mandb(8) Documentation for some packages may be available in other formats, such as info(1) or HTML. HISTORY 1990, 1991 – Originally written by John W. Eaton (jwe@che.utexas.edu). Dec 23 1992: Rik Faith (faith@cs.unc.edu) applied bug fixes supplied by Willem Kasdorp (wkasdo@nikhefk.nikef.nl). 30th April 1994 – 23rd February 2000: Wilf. (G.Wilford@ee.surrey.ac.uk) has been developing and maintaining this package with the help of a few dedicated people. 30th October 1996 – 30th March 2001: Fabrizio Polacco <fpolacco@debian.org> maintained and enhanced this package for the Debian project, with the help of all the community. 31st March 2001 – present day: Colin Watson <cjwatson@debian.org> is now developing and maintaining man‐db. BUGS https://gitlab.com/man‐db/man‐db/‐/issues https://savannah.nongnu.org/bugs/?group=man‐db 2.11.2 2023‐01‐08 MAN(1)

This section details environment variables like `MAN_KEEP_FORMATTING` (retains formatting characters), `MAN_KEEP_STDERR` (displays error output), and `MAN_DISABLE_SECCOMP` (disables the seccomp sandbox). It also covers the `PIPELINE_DEBUG` variable for debugging subprocesses and `LANG`, `LC_MESSAGES` for localization. It lists the configuration file `/etc/manpath.config` and the global manual page hierarchy `/usr/share/man`. Additionally, it includes a list of related utilities, a brief history of the `man` command's development, and links to bug reporting resources.