76 lines
1.8 KiB
Groff
76 lines
1.8 KiB
Groff
.\" Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
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.\" Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
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.\"
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.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
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.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
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.TH npc 1
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.SH NAME
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npc \(en show non-printing characters
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.SH SYNOPSIS
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npc
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.RB ( -et )
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.SH DESCRIPTION
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Print normally non-printing characters.
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The program reads from standard input and writes to standard output, replacing
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non-printing characters with printable equivalents. Control characters print as
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a carat ('^') followed by the character '@' through '_' corresponding to the
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character replaced (e.g. control-X becomes '^X'). The delete character (0x7F)
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becomes '^?'. Characters with the high bit set (>127) are printed as 'M-'
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followed by the graphical representation for the same character without the
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high bit set.
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.SH USAGE
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.B -e
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.RS
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Prints a currency sign ('$') before each line ending.
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.RE
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.B -t
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.RS
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Prints tab characters as '^I' rather than a literal horizontal tab.
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.RE
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.SH DIAGNOSTICS
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In the event of an error, a debug message will be printed and the program will
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exit with the appropriate sysexits.h(3) error code.
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.SH BUGS
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The program operates in single-byte chunks regardless of intended encoding.
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.SH RATIONALE
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POSIX currently lacks a way to display non-printing characters in the terminal
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using a standard tool. A popular extension to cat(1p), the
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.B -v
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option, is the bandage solution GNU and other software suites use.
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This functionality is a separate tool because its usefulness extends beyond that
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of cat(1p).
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.SH AUTHOR
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Written by DTB <trinity@trinity.moe>.
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.SH COPYRIGHT
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Copyright © 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
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<https://gnu.org/licenses/agpl.html>.
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.SH SEE ALSO
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cat(1p), cat-v(1)
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.I UNIX Style, or cat -v Considered Harmful
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by Rob Pike
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