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http://bugs.gentoo.org/337329
http://bugs.gentoo.org/527848
there's no requirement for `echo` to support escape sequences. bash, by default,
does not, while dash always does. POSIX permits either behavior:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/echo.html
however, since the behavior is not portable, no one should be relying on echo
having any specific behavior. they should use `printf` when they want an escape
sequence. it also makes dash smaller & faster to disable this logic entirely.
--- a/src/bltin/printf.c
+++ b/src/bltin/printf.c
@@ -439,34 +444,12 @@
int
echocmd(int argc, char **argv)
{
- int nonl = 0;
- struct output *outs = out1;
-
- if (!*++argv)
- goto end;
- if (equal(*argv, "-n")) {
- nonl = ~nonl;
- if (!*++argv)
- goto end;
+ int i;
+ for (i = 1; i < argc; ++i) {
+ outstr(argv[i], out1);
+ if (i < argc - 1)
+ outc(' ', out1);
}
-
- do {
- int c;
-
- nonl += conv_escape_str(*argv);
- outstr(stackblock(), outs);
- if (nonl > 0)
- break;
-
- c = ' ';
- if (!*++argv) {
-end:
- if (nonl) {
- break;
- }
- c = '\n';
- }
- outc(c, outs);
- } while (*argv);
+ outc('\n', out1);
return 0;
}
--- a/src/dash.1
+++ b/src/dash.1
@@ -1180,43 +1180,15 @@
option turns off the effect of any preceding
.Fl P
options.
-.It Xo echo Op Fl n
+.It Xo echo
.Ar args...
.Xc
Print the arguments on the standard output, separated by spaces.
-Unless the
-.Fl n
-option is present, a newline is output following the arguments.
-.Pp
-If any of the following sequences of characters is encountered during
-output, the sequence is not output. Instead, the specified action is
-performed:
-.Bl -tag -width indent
-.It Li \eb
-A backspace character is output.
-.It Li \ec
-Subsequent output is suppressed. This is normally used at the end of the
-last argument to suppress the trailing newline that
-.Ic echo
-would otherwise output.
-.It Li \ef
-Output a form feed.
-.It Li \en
-Output a newline character.
-.It Li \er
-Output a carriage return.
-.It Li \et
-Output a (horizontal) tab character.
-.It Li \ev
-Output a vertical tab.
-.It Li \e0 Ns Ar digits
-Output the character whose value is given by zero to three octal digits.
-If there are zero digits, a nul character is output.
-.It Li \e\e
-Output a backslash.
-.El
.Pp
-All other backslash sequences elicit undefined behaviour.
+No arguments or backslash sequences are supported as they are not portable.
+They will be printed out exactly as passed in.
+.Pp
+You can replace `echo -n ...` with the portable `printf %s ...` construct.
.It eval Ar string ...
Concatenate all the arguments with spaces.
Then re-parse and execute the command.
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