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How do I distinguish between a command, utility, or builtin for getting documentation?
March 19, 2018
Edited: March 19, 2018
November 24, 2022
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Some builtin commands are included for efficiency sake and exist as external commands in the first place. For example:
$ type -a echo echo is a shell builtin echo is /bin/echo $ type -a printf printf is a shell builtin printf is /usr/bin/printf
A detailed analysis of builtins and external commands can be found in Unix & Linux.
As far as getting help for dual builtins/external commands such as
echo you have two choices. One method is by using
ECHO(1) User Commands ECHO(1) NAME echo - display a line of text SYNOPSIS echo [SHORT-OPTION]... [STRING]... echo LONG-OPTION DESCRIPTION Echo the STRING(s) to standard output. -n do not output the trailing newline -e enable interpretation of backslash escapes -E disable interpretation of backslash escapes (default) --help display this help and exit --version output version information and exit If -e is in effect, the following sequences are recognized: \\ backslash \a alert (BEL) Manual page echo(1) line 1 (press h for help or q to quit)
And you can type:
$ help echo echo: echo [-neE] [arg ...] Write arguments to the standard output. Display the ARGs, separated by a single space character and followed by a newline, on the standard output. Options: -n do not append a newline -e enable interpretation of the following backslash escapes -E explicitly suppress interpretation of backslash escapes `echo' interprets the following backslash-escaped characters: \a alert (bell) \b backspace \c suppress further output \e escape character \E escape character \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \\ backslash \0nnn the character whose ASCII code is NNN (octal). NNN can be 0 to 3 octal digits \xHH the eight-bit character whose value is HH (hexadecimal). HH can be one or two hex digits Exit Status: Returns success unless a write error occurs.