[1/5] kheaders: remove unneeded 'cat' command piped to 'head' / 'tail'
diff mbox series

Message ID 20191008120556.4263-1-yamada.masahiro@socionext.com
State New
Headers show
Series
  • [1/5] kheaders: remove unneeded 'cat' command piped to 'head' / 'tail'
Related show

Commit Message

Masahiro Yamada Oct. 8, 2019, 12:05 p.m. UTC
The 'head' and 'tail' commands can take a file path directly.
So, you do not need to run 'cat'.

  cat kernel/kheaders.md5 | head -1

... is equivalent to:

  head -1 kernel/kheaders.md5

and the latter saves forking one process.

While I was here, I replaced 'head -1' with 'head -n 1'.

I also replaced '==' with '=' since we do not have a good reason to
use the bashism.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 kernel/gen_kheaders.sh | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Masahiro Yamada Oct. 24, 2019, 5:19 p.m. UTC | #1
On Tue, Oct 8, 2019 at 9:06 PM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> The 'head' and 'tail' commands can take a file path directly.
> So, you do not need to run 'cat'.
>
>   cat kernel/kheaders.md5 | head -1
>
> ... is equivalent to:
>
>   head -1 kernel/kheaders.md5
>
> and the latter saves forking one process.
>
> While I was here, I replaced 'head -1' with 'head -n 1'.
>
> I also replaced '==' with '=' since we do not have a good reason to
> use the bashism.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---

Series, applied to linux-kbuild.


>
>  kernel/gen_kheaders.sh | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh
> index aff79e461fc9..8aa6d3c37ba7 100755
> --- a/kernel/gen_kheaders.sh
> +++ b/kernel/gen_kheaders.sh
> @@ -41,10 +41,10 @@ obj_files_md5="$(find $dir_list -name "*.h"                    |
>  this_file_md5="$(ls -l $sfile | md5sum | cut -d ' ' -f1)"
>  if [ -f $tarfile ]; then tarfile_md5="$(md5sum $tarfile | cut -d ' ' -f1)"; fi
>  if [ -f kernel/kheaders.md5 ] &&
> -       [ "$(cat kernel/kheaders.md5|head -1)" == "$src_files_md5" ] &&
> -       [ "$(cat kernel/kheaders.md5|head -2|tail -1)" == "$obj_files_md5" ] &&
> -       [ "$(cat kernel/kheaders.md5|head -3|tail -1)" == "$this_file_md5" ] &&
> -       [ "$(cat kernel/kheaders.md5|tail -1)" == "$tarfile_md5" ]; then
> +       [ "$(head -n 1 kernel/kheaders.md5)" = "$src_files_md5" ] &&
> +       [ "$(head -n 2 kernel/kheaders.md5 | tail -n 1)" = "$obj_files_md5" ] &&
> +       [ "$(head -n 3 kernel/kheaders.md5 | tail -n 1)" = "$this_file_md5" ] &&
> +       [ "$(tail -n 1 kernel/kheaders.md5)" = "$tarfile_md5" ]; then
>                 exit
>  fi
>
> --
> 2.17.1
>

Patch
diff mbox series

diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh
index aff79e461fc9..8aa6d3c37ba7 100755
--- a/kernel/gen_kheaders.sh
+++ b/kernel/gen_kheaders.sh
@@ -41,10 +41,10 @@  obj_files_md5="$(find $dir_list -name "*.h"			   |
 this_file_md5="$(ls -l $sfile | md5sum | cut -d ' ' -f1)"
 if [ -f $tarfile ]; then tarfile_md5="$(md5sum $tarfile | cut -d ' ' -f1)"; fi
 if [ -f kernel/kheaders.md5 ] &&
-	[ "$(cat kernel/kheaders.md5|head -1)" == "$src_files_md5" ] &&
-	[ "$(cat kernel/kheaders.md5|head -2|tail -1)" == "$obj_files_md5" ] &&
-	[ "$(cat kernel/kheaders.md5|head -3|tail -1)" == "$this_file_md5" ] &&
-	[ "$(cat kernel/kheaders.md5|tail -1)" == "$tarfile_md5" ]; then
+	[ "$(head -n 1 kernel/kheaders.md5)" = "$src_files_md5" ] &&
+	[ "$(head -n 2 kernel/kheaders.md5 | tail -n 1)" = "$obj_files_md5" ] &&
+	[ "$(head -n 3 kernel/kheaders.md5 | tail -n 1)" = "$this_file_md5" ] &&
+	[ "$(tail -n 1 kernel/kheaders.md5)" = "$tarfile_md5" ]; then
 		exit
 fi