This Web page is written in Texinfo, the GNU documentation formatting language. A single Texinfo source file is used to produce both the printed and online versions of the documentation. Because of this, the typographical conventions are slightly different than in other books you may have read.
Examples you would type at the command line are preceded by the common shell primary and secondary prompts, ‘$’ and ‘>’. Input that you type is shown like this. Output from the command is preceded by the glyph “-|”. This typically represents the command’s standard output. Error messages and other output on the command’s standard error are preceded by the glyph “error→”. For example:
$ echo hi on stdout -| hi on stdout $ echo hello on stderr 1>&2 error→ hello on stderr
In the text, almost anything related to programming, such as command
names, variable and function names, and string, numeric and regexp
constants appear in this font. Code fragments appear in the same
font and quoted, ‘like this’. Things that are replaced by the
user or programmer appear in this font. Options look like this:
-f. File names are indicated like this: /path/to/ourfile.
Some things are emphasized like this, and if a point needs to be
made strongly, it is done like this. The first occurrence of
a new term is usually its definition and appears in the same font
as the previous occurrence of “definition” in this sentence.
Characters that you type at the keyboard look like this. In particular, there are special characters called “control characters.” These are characters that you type by holding down both the CONTROL key and another key, at the same time. For example, a Ctrl-d is typed by first pressing and holding the CONTROL key, next pressing the d key, and finally releasing both keys.
NOTE: Notes of interest look like this.
CAUTION: Cautionary or warning notes look like this.