* [PATCH 1/1] cmd: change suppress newline in echo command
@ 2021-01-20 16:43 Heinrich Schuchardt
2021-01-21 3:26 ` Simon Glass
0 siblings, 1 reply; 2+ messages in thread
From: Heinrich Schuchardt @ 2021-01-20 16:43 UTC (permalink / raw)
To: u-boot
By default the echo command emits its arguments followed by a line feed.
If any of the arguments contains the sub-string "\c", the line feed is
suppressed.
This does not match shells used in Linux and BSD where the first argument
has to be -n to suppress the line feed.
The hush shell interferes with the parsing of backslashes. E.g. in the
following command line quadruple backslashes are required for suppressing
the line feed:
for i in 1 2 3; do for j in 4 5; do echo \\\\c ${i}${j}; done; echo; done;
To avoid unexpected behavior the patch changes echo to use -n as first
argument to suppress the line feed.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
cmd/echo.c | 49 ++++++++++++++++++-------------------------------
1 file changed, 18 insertions(+), 31 deletions(-)
diff --git a/cmd/echo.c b/cmd/echo.c
index d02a4cfd58..fda844ee9d 100644
--- a/cmd/echo.c
+++ b/cmd/echo.c
@@ -10,47 +10,34 @@
static int do_echo(struct cmd_tbl *cmdtp, int flag, int argc,
char *const argv[])
{
- int i;
- int putnl = 1;
-
- for (i = 1; i < argc; i++) {
- char *p = argv[i];
- char *nls; /* new-line suppression */
+ int i = 1;
+ bool space = false;
+ bool newline = true;
+
+ if (argc > 1) {
+ if (!strcmp(argv[1], "-n")) {
+ newline = false;
+ ++i;
+ }
+ }
- if (i > 1)
+ for (; i < argc; ++i) {
+ if (space) {
putc(' ');
-
- nls = strstr(p, "\\c");
- if (nls) {
- char *prenls = p;
-
- putnl = 0;
- /*
- * be paranoid and guess that someone might
- * say \c more than once
- */
- while (nls) {
- *nls = '\0';
- puts(prenls);
- *nls = '\\';
- prenls = nls + 2;
- nls = strstr(prenls, "\\c");
- }
- puts(prenls);
- } else {
- puts(p);
}
+ puts(argv[i]);
+ space = true;
}
- if (putnl)
+ if (newline)
putc('\n');
return 0;
}
U_BOOT_CMD(
- echo, CONFIG_SYS_MAXARGS, 1, do_echo,
+ echo, CONFIG_SYS_MAXARGS, 1, do_echo,
"echo args to console",
- "[args..]\n"
- " - echo args to console; \\c suppresses newline"
+ "[-n] [args..]\n"
+ " - echo args to console; -n suppresses newline"
);
--
2.29.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 1/1] cmd: change suppress newline in echo command
2021-01-20 16:43 [PATCH 1/1] cmd: change suppress newline in echo command Heinrich Schuchardt
@ 2021-01-21 3:26 ` Simon Glass
0 siblings, 0 replies; 2+ messages in thread
From: Simon Glass @ 2021-01-21 3:26 UTC (permalink / raw)
To: u-boot
Hi Heinrich,
On Wed, 20 Jan 2021 at 09:43, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>
> By default the echo command emits its arguments followed by a line feed.
>
> If any of the arguments contains the sub-string "\c", the line feed is
> suppressed.
>
> This does not match shells used in Linux and BSD where the first argument
> has to be -n to suppress the line feed.
>
> The hush shell interferes with the parsing of backslashes. E.g. in the
> following command line quadruple backslashes are required for suppressing
> the line feed:
>
> for i in 1 2 3; do for j in 4 5; do echo \\\\c ${i}${j}; done; echo; done;
>
> To avoid unexpected behavior the patch changes echo to use -n as first
> argument to suppress the line feed.
>
> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> ---
> cmd/echo.c | 49 ++++++++++++++++++-------------------------------
> 1 file changed, 18 insertions(+), 31 deletions(-)
Reviewed-by: Simon Glass <sjg@chromium.org>
This could be a good oppty to add a test for the echo command.
^ permalink raw reply [flat|nested] 2+ messages in thread
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