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A page for each applet in the kit, plus .so stubs for aliases such as egrep and unxz. Each was written from the pinned busybox-w32 source with the kit's patches and configuration, then checked against the source and by experiment. The NOTES sections cover Windows behavior. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
341 lines
6.6 KiB
Groff
341 lines
6.6 KiB
Groff
.TH ECHO 1 2026-10-19 "w64devkit" "w64devkit Manual"
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.SH NAME
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echo \- write arguments to standard output
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.SH SYNOPSIS
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.B echo
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.RB [ \-neE ]
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.RI [ arg ...]
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.SH DESCRIPTION
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.B echo
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writes its arguments to standard output, separated by single spaces and
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followed by a newline.
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With no arguments it writes only the newline.
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It reads no input.
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.PP
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Arguments are written byte for byte.
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In particular, a backslash is an ordinary character unless
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.B \-e
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is given.
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.PP
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The kit's shell has
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.B echo
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as a builtin that runs this same code, so scripts see the behavior
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described here; see
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.BR sh (1).
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Outside the shell, the
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.I echo.exe
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launcher runs the
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.B busybox
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applet; see
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.BR busybox (1).
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.SS Escape sequences
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With
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.BR \-e ,
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a backslash in an argument starts an escape sequence, which is replaced
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as follows.
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.TP
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.B \ea
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Alert (BEL, 0x07).
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.TP
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.B \eb
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Backspace (0x08).
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.TP
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.B \ec
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Stop: write nothing more, not even the newline.
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Output from before it is kept, but the rest of this argument and all
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later arguments are dropped.
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.TP
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.B \ee
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Escape (0x1B).
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.TP
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.B \ef
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Form feed (0x0C).
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.TP
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.B \en
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Line feed (0x0A).
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.TP
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.B \er
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Carriage return (0x0D).
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.TP
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.B \et
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Tab (0x09).
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.TP
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.B \ev
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Vertical tab (0x0B).
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.TP
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.B \e\e
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Backslash.
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.TP
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\fB\e0\fInnn\fR, \fB\e\fInnn\fR
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The octet whose octal value is
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.IR nnn .
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Either a
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.B \e0
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and up to three octal digits, or one to three octal digits the first of
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which is 1 to 7.
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A value above 255 ends the sequence before the digit that would exceed
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it, so
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.B \e400
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is a space (octal 40) followed by
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.BR 0 .
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A
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.B \e0
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that is not followed by an octal digit is a NUL octet.
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.TP
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.BI \ex HH
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The octet whose hexadecimal value is
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.IR HH ,
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one or two digits in either case.
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A
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.B \ex
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not followed by a hexadecimal digit is written as is.
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.PP
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A backslash followed by any other character, or ending an argument, is
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written as is, and the character after it is then read normally.
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So
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.B \eE
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and
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.B \eu0041
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are written unchanged.
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.SH OPTIONS
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Options are recognized only at the start of the arguments, and may be
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grouped, as in
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.BR \-ne .
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An argument is an option only if it is a dash followed by one or more of
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the letters
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.BR n ,
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.BR e ,
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and
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.BR E .
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The first argument that is not, such as
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.BR \-\- ,
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a lone
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.BR \- ,
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.BR \-x ,
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or
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.BR \-nx ,
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ends the options: it and all later arguments are written as ordinary
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arguments.
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Neither
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.B \-\-
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nor
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.B \-\-help
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is special: they are written like any other argument.
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.TP
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.B \-n
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Do not write the trailing newline.
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.TP
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.B \-e
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Interpret backslash escape sequences, as described under
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.BR "Escape sequences" .
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.TP
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.B \-E
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Do not interpret backslash escape sequences.
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This is the default.
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It does not cancel an earlier
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.BR \-e :
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both
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.B "echo \-e \-E"
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and
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.B "echo \-E \-e"
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interpret escapes.
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.SH ENVIRONMENT
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.TP
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.B BB_GLOBBING
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Unless it is
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.BR 0 ,
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wildcards in the arguments are expanded, as needed when run from
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.BR cmd.exe .
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A busybox process started with it unset sets it to
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.B 0
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for its children, so commands run from the kit's shell receive their
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arguments as the shell expanded them.
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.TP
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.BR BB_TERMINAL_MODE ", " BB_SKIP_ANSI_EMULATION
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When standard output is a console, decide whether the console or busybox
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interprets the escape sequences in the output, such as for color.
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See
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.BR busybox (1).
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.TP
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.B CONEMUPID
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When it is set and neither of the above is, busybox uses terminal mode
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0: it turns virtual terminal output off and emulates escape sequences
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itself.
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.TP
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.BR LC_ALL ", " LC_CTYPE ", " LANG
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If the first of these that is set has the value
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.BR C ,
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output to a console is not converted, as described in
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.BR NOTES ,
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and the console interprets the bytes in its own code page.
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.PP
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Variables that affect every busybox applet are described in
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.BR busybox (1).
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.SH EXIT STATUS
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.TP
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.B 0
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Success.
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.TP
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.B 1
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Standard output could not be written.
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A message such as
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.B "echo: write error: Bad file descriptor"
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is written to standard error.
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In the shell's builtin the message begins with the shell's name, such as
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.BR sh: ,
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instead.
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.TP
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.B 141
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Standard output is a pipe that was closed before the output was written.
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In the shell's builtin, the shell process running it exits with this status.
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.SH EXAMPLES
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Write a line:
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.PP
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.RS 4
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.EX
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$ echo hello world
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hello world
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.EE
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.RE
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.PP
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Write a prompt, leaving the cursor on the same line:
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.PP
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.RS 4
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.EX
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$ echo \-n \(aqContinue? \(aq
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.EE
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.RE
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.PP
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Without
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.BR \-e ,
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backslashes are written as is:
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.PP
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.RS 4
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.EX
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$ echo \(aqone\entwo\(aq
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one\entwo
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$ echo \-e \(aqone\entwo\(aq
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one
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two
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.EE
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.RE
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.PP
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Write a file with CR LF line endings:
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.PP
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.RS 4
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.EX
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$ echo \-e \(aqfirst\er\(aq >dos.txt
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$ echo \-e \(aqsecond\er\(aq >>dos.txt
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.EE
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.RE
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.PP
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Write a word in red on a console:
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.PP
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.RS 4
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.EX
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$ echo \-e \(aq\ee[31mred\ee[0m\(aq
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.EE
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.RE
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.PP
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Write a string that
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.B echo
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would take as an option, using
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.BR printf (1)
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instead:
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.PP
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.RS 4
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.EX
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$ printf \(aq%s\en\(aq \-n
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\-n
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.EE
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.RE
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.SH NOTES
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Differences from GNU
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.B echo
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and bash:
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.IP \(bu 2
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A later
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.B \-E
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does not turn off an earlier
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.BR \-e .
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.IP \(bu 2
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An octal value above 255 ends the escape sequence early instead of
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wrapping modulo 256.
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.IP \(bu 2
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As in GNU
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.B echo
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but not bash, an octal escape may omit the leading zero:
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.B \e101
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is
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.BR A .
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.IP \(bu 2
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The bash escapes
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.BR \eE ,
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.BR \eu ,
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and
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.B \eU
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are not recognized.
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.IP \(bu 2
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Unlike GNU
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.BR echo ,
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there are no
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.B \-\-help
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or
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.B \-\-version
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options.
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.PP
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Standard output is binary, so the newline is a bare LF.
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To end a line with CR LF, use
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.B \-e
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and
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.BR \er .
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.PP
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In
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.BR cmd.exe ,
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.B echo
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is a built-in command that runs instead of the applet, and in PowerShell
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it is an alias for
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.BR Write-Output .
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Run
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.B echo.exe
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or
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.B busybox echo
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there.
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Since the C runtime then expands wildcards, even in quoted arguments,
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.B echo.exe *.c
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lists the matching files; set
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.B BB_GLOBBING
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to
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.B 0
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to prevent that.
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.PP
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With
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.BR \-e ,
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a backslash in a Windows path is an escape: in
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.BR C:\etemp ,
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.B \et
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is a tab.
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Write such paths with forward slashes, or leave out
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.BR \-e .
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In the kit's shell, quote such an argument in single quotes: unquoted,
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the shell removes the backslash before
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.B echo
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sees it.
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.PP
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Arguments may contain any Unicode character on Windows 10 version 1903
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and later, and are limited to the system code page on earlier versions.
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When standard output is a console, the output is converted for display
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from the ANSI code page, which is UTF-8 on Windows 10 version 1903 and
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later.
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Escape sequences, such as those for color, take effect, and busybox
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emulates them on consoles without virtual terminal support.
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The whole output is one block, so on a console a NUL octet in it, such
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as from
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.BR \e0 ,
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makes busybox write all of it unconverted and without escape sequence
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emulation.
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.SH SEE ALSO
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.BR busybox (1),
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.BR printf (1),
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.BR sh (1)
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