Re: portable use of 'dd'

[Bruno Haible]

Hi GNU standards maintainers,

Jim Meyering wrote in [1]
>       use dd ibs=$n count=1 ... rather than less-portable head -c$n

The GNU standards, section "Utilities in Makefiles", do not mention 'dd'
among the list of utilities whose existence can be assumed everywhere.

But on all platforms that I tested (including old ones like IRIX 6.5, OSF/1 4.0,
Solaris 2.5.1), 'dd' exists, and
  $ echo abcdef | dd ibs=4 count=1 2>/dev/null; echo
yields the output
  abcd

Therefore I would suggest to add 'dd' among the "safe" utilities.

--- doc/make-stds.texi.orig     2008-05-14 23:15:34.000000000 +0200
+++ doc/make-stds.texi  2008-05-14 23:15:17.000000000 +0200
@@ -160,7 +160,7 @@
 @c mkfifo mknod tee uname
 
 @example
-awk cat cmp cp diff echo egrep expr false grep install-info
+awk cat cmp cp dd diff echo egrep expr false grep install-info
 ln ls mkdir mv pwd rm rmdir sed sleep sort tar test touch true
 @end example
 

Bruno


[1] http://lists.gnu.org/archive/html/bug-gnulib/2008-05/msg00067.html