Bdtyktl

I'm running Bash scripting, but sometimes I get confused which of these commands I use belong to who. Sometimes man xxx works, sometimes doesn't, so I use --help or info, mostly one of these works to show description of the command. Can anyone tell me how I would know what command belongs to what? Bash builtin, GNU utility, etc.

You can use type to find out:

$ type echo

echo is a shell builtin

$ type sudo

sudo is /usr/bin/sudo

For bash builtins, use help, as in help echo.

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 man echo:

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

      nnn 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.