Otto Moerbeek wrote:
On Fri, Mar 14, 2008 at 09:02:19PM +1300, Richard Toohey wrote:
On 14/03/2008, at 8:31 PM, Richard Toohey wrote:
On 14/03/2008, at 8:15 PM, Erwin van Maanen wrote:
if [ X"${dhcpd_flags}" != X"NO" -a -f /etc/dhcpd.conf ]; then
Now i have no clue what " -a -f " does (anyone care to point me to the
right
manual?)
[cut]
man test
-f file True if file exists and is a regular file.
expression1 -a expression2
True if both expression1 and expression2 are true.
Apologies to all who know this already - but I wondered about that [ file
for ages until I was enlightened.
So, if you are wondering why man test ... at the top of the man page:
SYNOPSIS
test expression
[ expression ]
(See the square brackets?) And if you look in /bin:
$ ls -l /bin
total 13652
-r-xr-xr-x 2 root bin 79136 Aug 29 2007 [
[cut]
-r-xr-xr-x 2 root bin 79136 Aug 29 2007 test
man [ will take you to the test man page.
See, for example:
http://developer.apple.com/documentation/OpenSource/Conceptual/ShellScripting/shell_scripts/chapter_2_section_10.html#//apple_ref/doc/uid/TP40004268-CH237-SW4
Some background...
Originally, the shell had vitually no builtin commands, all processing
was done by external commands. Even loops were implemented by forking
a child that interpreted the condition and moved the seek position in
the shell script being executed. That could be done since fd's were
shared.
Of course that was all dog slow, and that's why more and more commands
are now executed as builtins. External version of the commands still
remain, though.
... which means that people should actually have pointed the OP top
ksh(1) rather than test(1) or [(1)... :-)
/Alexander
