diff mbox series

[v2,1/1] t0003: Call dd with portable blocksize

Message ID 20230122062839.14542-1-tboegi@web.de (mailing list archive)
State New, archived
Headers show
Series [v2,1/1] t0003: Call dd with portable blocksize | expand

Commit Message

Torsten Bögershausen Jan. 22, 2023, 6:28 a.m. UTC 
From: Torsten Bögershausen <tboegi@web.de>

The command `dd bs=101M count=1` is not portable,
e.g. dd shipped with MacOs does not understand the 'M'.

Use `bs=1048576 count=101`, which achives the same, instead.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
---
 t/t0003-attributes.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--
2.39.1.254.g904d404274

Comments

Junio C Hamano Jan. 22, 2023, 4:21 p.m. UTC | #1 
tboegi@web.de writes:

> From: Torsten Bögershausen <tboegi@web.de>
>
> The command `dd bs=101M count=1` is not portable,
> e.g. dd shipped with MacOs does not understand the 'M'.

Very good piece of information to have here.

> Use `bs=1048576 count=101`, which achives the same, instead.

I'd locally tweak (read: no need to resend) it to

    Use `dd bs=1048576 count=101`, which ...

and downcase "Call" on the title line.

A tangent.  I wonder how portable 

    dd bs=1024x1024 count=101
    dd bs=1kx1k count=101

are in practice.  "Two or more positive decimal numbers (with or
without 'k' or 'b') separated by 'x', specifying the product of the
indicated values" is from POSIX, but I haven't used it myself (I
know GNU dd groks it).

In any case, thanks for the update.
Torsten Bögershausen Jan. 22, 2023, 6 p.m. UTC | #2 
On Sun, Jan 22, 2023 at 08:21:45AM -0800, Junio C Hamano wrote:
> tboegi@web.de writes:
>
> > From: Torsten Bögershausen <tboegi@web.de>
> >
> > The command `dd bs=101M count=1` is not portable,
> > e.g. dd shipped with MacOs does not understand the 'M'.
>
> Very good piece of information to have here.
>
> > Use `bs=1048576 count=101`, which achives the same, instead.
>
> I'd locally tweak (read: no need to resend) it to
>
>     Use `dd bs=1048576 count=101`, which ...
>
> and downcase "Call" on the title line.
>
> A tangent.  I wonder how portable
>
>     dd bs=1024x1024 count=101
This works all Unix-ish system I have: both on MacOs and FreeBSD.

>     dd bs=1kx1k count=101
Works on FreeBSD.
Does not work under MacOS: "dd: bs: illegal numeric value"


> In any case, thanks for the update.

Thanks for the review and the tweaking.
diff mbox series

Patch

diff --git a/t/t0003-attributes.sh b/t/t0003-attributes.sh
index d0284fe2d7..394a08e6d6 100755
--- a/t/t0003-attributes.sh
+++ b/t/t0003-attributes.sh
@@ -400,7 +400,7 @@  test_expect_success 'large attributes line ignores trailing content in tree' '

 test_expect_success EXPENSIVE 'large attributes file ignored in tree' '
 	test_when_finished "rm .gitattributes" &&
-	dd if=/dev/zero of=.gitattributes bs=101M count=1 2>/dev/null &&
+	dd if=/dev/zero of=.gitattributes bs=1048576 count=101 2>/dev/null &&
 	git check-attr --all path >/dev/null 2>err &&
 	echo "warning: ignoring overly large gitattributes file ${SQ}.gitattributes${SQ}" >expect &&
 	test_cmp expect err
@@ -428,7 +428,7 @@  test_expect_success 'large attributes line ignores trailing content in index' '

 test_expect_success EXPENSIVE 'large attributes file ignored in index' '
 	test_when_finished "git update-index --remove .gitattributes" &&
-	blob=$(dd if=/dev/zero bs=101M count=1 2>/dev/null | git hash-object -w --stdin) &&
+	blob=$(dd if=/dev/zero bs=1048576 count=101 2>/dev/null | git hash-object -w --stdin) &&
 	git update-index --add --cacheinfo 100644,$blob,.gitattributes &&
 	git check-attr --cached --all path >/dev/null 2>err &&
 	echo "warning: ignoring overly large gitattributes blob ${SQ}.gitattributes${SQ}" >expect &&