[gentoo-user] strange [ file

[gentoo-user] strange [ file

[Arnau Bria]

Hi,

I've seen a file named "[" in my /usr/bin ...

#file "["
[: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), for
GNU/Linux 2.4.1, dynamically linked (uses shared libs), for GNU/Linux
2.4.1, stripped

in I can find things like:
[...]
-ot does not accept -l
%s: unary operator expected
%s: binary operator expected
')' expected, found %s
')' expected
test and/or [
Report bugs to <%s>.
bug-coreutils at gnu.org/usr/share/localeMatthew BradburnKevin
Braunsdorf5.94GNU coreutilsmissing `]' Try `%s --help' for more
information. Usage: test EXPRESSION
  or:  test
  or:  [ EXPRESSION ]
  or:  [ ]
  or:  [ OPTION
Exit with the status determined by EXPRESSION.
[...]

does any one know what could it be?¿
thanks in advance.
-- 
Arnau Bria
http://blog.emergetux.net
La vida es una aplastante derrota tras otra hasta que 
acabas deseando que se muera Flanders.
~Homer J. Simpson~
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Re: [gentoo-user] strange [ file

[Dale]

Arnau Bria wrote:
> Hi,
>
> I've seen a file named "[" in my /usr/bin ...
>
> #file "["
> [: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), for
> GNU/Linux 2.4.1, dynamically linked (uses shared libs), for GNU/Linux
> 2.4.1, stripped
>
> in I can find things like:
> [...]
> -ot does not accept -l
> %s: unary operator expected
> %s: binary operator expected
> ')' expected, found %s
> ')' expected
> test and/or [
> Report bugs to <%s>.
> bug-coreutils at gnu.org/usr/share/localeMatthew BradburnKevin
> Braunsdorf5.94GNU coreutilsmissing `]' Try `%s --help' for more
> information. Usage: test EXPRESSION
>   or:  test
>   or:  [ EXPRESSION ]
>   or:  [ ]
>   or:  [ OPTION
> Exit with the status determined by EXPRESSION.
> [...]
>
> does any one know what could it be?¿
> thanks in advance.
>   

This may help a little:

> root@smoker / # equery belongs [
> [ Searching for file(s) [ in *... ]
> sys-apps/coreutils-5.94-r1 (/usr/bin/[)
> root@smoker / #

It's part of coreutils.  At least someone isn't putting something on
your system you don't know about.

It is weird that they named it that though.

Dale
:-)  :-)

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Re: [gentoo-user] strange [ file

[Christoph Eckert]

> does any one know what could it be?¿

AFAIK it's a synonym to »test«.


Best regards


ce

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Re: [gentoo-user] strange [ file

[Richard Fish]

On 7/25/06, Arnau Bria <arnau@emergetux.net> wrote:
> Hi,
>
> I've seen a file named "[" in my /usr/bin ...

Perfectly normal.  It is a program that implements bash style tests
for script environments that don't normally do them.  For example:

if [ -f /etc/passwd ] ; then
  echo "/etc/passwd exists and is a regular file"
fi

Notice the "[" after the "if"....

"man test" will give you the user manual for it.

More generally, merge gentoolkit, and you can use equery to find out
where things come from.  Ex:

~ > equery belongs "/usr/bin/["
[ Searching for file(s) /usr/bin/[ in *... ]
sys-apps/coreutils-5.97 (/usr/bin/[)
~ > equery check coreutils
[ Checking sys-apps/coreutils-5.97 ]
 * 318 out of 318 files good

-Richard
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Re: [gentoo-user] strange [ file

[Dirk Heinrichs]

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Am Dienstag, 25. Juli 2006 11:00 schrieb ext Arnau Bria:

> I've seen a file named "[" in my /usr/bin ...
> [...]
>
> does any one know what could it be?¿

It's the [ from "if [ condition ]; then ...", a shortcut for /usr/bin/test.

HTH...

	Dirk
-- 
Dirk Heinrichs          | Tel:  +49 (0)162 234 3408
Configuration Manager   | Fax:  +49 (0)211 47068 111
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Re: [gentoo-user] strange [ file

[Neil Bothwick]

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On Tue, 25 Jul 2006 11:00:38 +0200, Arnau Bria wrote:

> I've seen a file named "[" in my /usr/bin ...

[ is a synonym for the test command, see man test for details.

This file isn't normally used, because [ and test are builtins in Bash.


-- 
Neil Bothwick

Some day my ship will come in, but with my luck, I'll be at the airport.

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[gentoo-user] Re: strange [ file

[Marco Costa]

Arnau Bria wrote:
> I've seen a file named "[" in my /usr/bin ...
> ...
> does any one know what could it be?¿
> thanks in advance.

It is the test application/tool. Try 'info test'.

Regards,

Marco

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Re: [gentoo-user] strange [ file

[Arnau Bria]

On Tue, 25 Jul 2006 02:14:02 -0700
Richard Fish wrote:

> On 7/25/06, Arnau Bria <arnau@emergetux.net> wrote:
> > Hi,
> >
> > I've seen a file named "[" in my /usr/bin ...
> 
> Perfectly normal.  It is a program that implements bash style tests
> for script environments that don't normally do them.  For example:
> 
> if [ -f /etc/passwd ] ; then
>   echo "/etc/passwd exists and is a regular file"
> fi
> 
> Notice the "[" after the "if"....
> 
> "man test" will give you the user manual for it.

Thanks, I'll take a look right now.
 
> More generally, merge gentoolkit, and you can use equery to find out
> where things come from.  Ex:

> ~ > equery belongs "/usr/bin/["
[...]
sure, but I supposed that if it was a strange file, it could come from
a corrupt source from coreutils. (I already looked for it with
equery, but its strange name make me confused).

I have a periodically rkhunter runnig in my system, but I was afraid I
got a corrupted source package...

> -Richard

even though answering only to Richard, thanks to all who answered my
question!

Cheers!

-- 
Arnau Bria
http://blog.emergetux.net
La vida es una aplastante derrota tras otra hasta que 
acabas deseando que se muera Flanders.
~Homer J. Simpson~
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Re: [gentoo-user] strange [ file

[Neil Bothwick]

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On Tue, 25 Jul 2006 11:36:55 +0200, Arnau Bria wrote:

> I have a periodically rkhunter runnig in my system, but I was afraid I
> got a corrupted source package...

Portage would refuse to install from a corrupted source package, because
it verifies the checksums of all files it uses.


-- 
Neil Bothwick

"Bother!." said Pooh, trying to uninstall freeserve from his PeeCee for
the umpteenth time.

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Re: [gentoo-user] strange [ file

[Alexander Skwar]

Richard Fish wrote:
> On 7/25/06, Arnau Bria <arnau@emergetux.net> wrote:
>> Hi,
>>
>> I've seen a file named "[" in my /usr/bin ...
> 
> Perfectly normal.  It is a program that implements bash style tests

Not *bash* style tests. bash doesn't have much to do with this.

> for script environments that don't normally do them.  For example:
> 
> if [ -f /etc/passwd ] ; then
>   echo "/etc/passwd exists and is a regular file"
> fi
> 
> Notice the "[" after the "if"....

However, [ is normally a shell builtin and thus /usr/bin/[ isn't
executed.

Alexander Skwar
-- 
Give a man a fish, and you feed him for a day.
Teach a man to fish, and he'll invite himself over for dinner.
- Calvin Keegan
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Re: [gentoo-user] strange [ file

[Alexander Skwar]

Dirk Heinrichs wrote:
> Am Dienstag, 25. Juli 2006 11:00 schrieb ext Arnau Bria:
> 
>> I've seen a file named "[" in my /usr/bin ...
>> [...]
>>
>> does any one know what could it be?¿
> 
> It's the [ from "if [ condition ]; then ...", a shortcut for /usr/bin/test.

Nope, not correct.

[09:39:58 vz6tml@dewup-ww02:~] $ type [
[ is a shell builtin
[13:01:25 vz6tml@dewup-ww02:~] $ type test
test is a shell builtin

And actually /usr/bin/[ and /usr/bin/test aren't even the same:

[13:01:56 vz6tml@dewup-ww02:~] $ ls -la /usr/bin/{[,test}
-rwxr-xr-x 1 root root 24852 27. Jun 09:34 /usr/bin/[
-rwxr-xr-x 1 root root 22784 27. Jun 09:34 /usr/bin/test

I wonder where the differences are. I would've expected that test and [
were hardlinks.

Alexander Skwar
-- 
Is it 1974?  What's for SUPPER?  Can I spend my COLLEGE FUND in one
wild afternoon??
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Re: [gentoo-user] strange [ file

[Dirk Heinrichs]

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Am Dienstag, 25. Juli 2006 13:02 schrieb ext Alexander Skwar:
> Dirk Heinrichs wrote:
> > Am Dienstag, 25. Juli 2006 11:00 schrieb ext Arnau Bria:
> >> I've seen a file named "[" in my /usr/bin ...
> >> [...]
> >>
> >> does any one know what could it be?¿
> >
> > It's the [ from "if [ condition ]; then ...", a shortcut for
> > /usr/bin/test.
>
> Nope, not correct.

OK: ... another form of /usr/bin/test. :-)

Bye...

	Dirk
-- 
Dirk Heinrichs          | Tel:  +49 (0)162 234 3408
Configuration Manager   | Fax:  +49 (0)211 47068 111
Capgemini Deutschland   | Mail: dirk.heinrichs@capgemini.com
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Re: [gentoo-user] strange [ file

[Neil Bothwick]

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On Tue, 25 Jul 2006 12:26:53 +0000, Hagen Soengen wrote:

> > I wonder where the differences are. I would've expected that test and
> > [ were hardlinks.
> 
> # /usr/bin/[
> 	/usr/bin/[: missing ']'
> # /usr/bin/test
> 	<no output>
> #
> 
> You see? They cant be the same, because the closing "]" is needed
> by /usr/bin[ and not by /usr/bin/test

It's quite common for a program to change its behaviour according to the
name used to run it. For example, zcat and gunzip are links to gzip, yet
the three programs behave differently.


-- 
Neil Bothwick

Stupid user error. Terminate user (Y/n) ?

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Re: [gentoo-user] strange [ file

[Mauro Faccenda]

On Tuesday 25 July 2006 09:20, Neil Bothwick wrote:
> On Tue, 25 Jul 2006 12:26:53 +0000, Hagen Soengen wrote:
> > > I wonder where the differences are. I would've expected that test and
> > > [ were hardlinks.
> >
> > # /usr/bin/[
> > 	/usr/bin/[: missing ']'
> > # /usr/bin/test
> > 	<no output>
> > #
> >
> > You see? They cant be the same, because the closing "]" is needed
> > by /usr/bin[ and not by /usr/bin/test
>
> It's quite common for a program to change its behaviour according to the
> name used to run it. For example, zcat and gunzip are links to gzip, yet
> the three programs behave differently.

but this isn't the case:

$ sha1sum /usr/bin/\[ /usr/bin/test
2d3a938b84db7107e323ac85a9bf4f351721da7b  /usr/bin/[
1b126dd3e41a2a9d4554879647f73fdf49d29479  /usr/bin/test

$ sha1sum /bin/zcat /bin/gzip /bin/gunzip
708011af43a41f6e3120e96eacb6ac4bba8717ee  /bin/zcat
708011af43a41f6e3120e96eacb6ac4bba8717ee  /bin/gzip
708011af43a41f6e3120e96eacb6ac4bba8717ee  /bin/gunzip

[]'s
	.m
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Re: [gentoo-user] strange [ file

[Hagen Soengen]

On Tue, 25 Jul 2006 13:02:48 +0200
Alexander Skwar <listen@alexander.skwar.name> wrote:

> Dirk Heinrichs wrote:
> > Am Dienstag, 25. Juli 2006 11:00 schrieb ext Arnau Bria:
> > 
> >> I've seen a file named "[" in my /usr/bin ...
> >> [...]
> >>
> >> does any one know what could it be?¿
> > 
> > It's the [ from "if [ condition ]; then ...", a shortcut for /usr/bin/test.
> 
> Nope, not correct.
> 
> [09:39:58 vz6tml@dewup-ww02:~] $ type [
> [ is a shell builtin
> [13:01:25 vz6tml@dewup-ww02:~] $ type test
> test is a shell builtin
> 
> And actually /usr/bin/[ and /usr/bin/test aren't even the same:
> 
> [13:01:56 vz6tml@dewup-ww02:~] $ ls -la /usr/bin/{[,test}
> -rwxr-xr-x 1 root root 24852 27. Jun 09:34 /usr/bin/[
> -rwxr-xr-x 1 root root 22784 27. Jun 09:34 /usr/bin/test
> 
> I wonder where the differences are. I would've expected that test and [
> were hardlinks.

# /usr/bin/[
	/usr/bin/[: missing ']'
# /usr/bin/test
	<no output>
#

You see? They cant be the same, because the closing "]" is needed by /usr/bin[ and not by /usr/bin/test

Hagen

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Re: [gentoo-user] strange [ file

[Neil Bothwick]

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On Tue, 25 Jul 2006 09:26:52 -0300, Mauro Faccenda wrote:

> > > You see? They cant be the same, because the closing "]" is needed
> > > by /usr/bin[ and not by /usr/bin/test
> >
> > It's quite common for a program to change its behaviour according to
> > the name used to run it. For example, zcat and gunzip are links to
> > gzip, yet the three programs behave differently.
> 
> but this isn't the case:

I was disagreeing with the "cant be the same" comment. I know they are
different files, but the slightly different behaviour is insufficient
reason for that. Alexander asked why one was not a link to the other, I'd
like to know too, but this isn't the reason.


-- 
Neil Bothwick

Top Oxymorons Number 47: Act naturally

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Re: [gentoo-user] strange [ file

[Alan McKinnon]

On Tue, 2006-07-25 at 14:16 +0100, Neil Bothwick wrote:
> On Tue, 25 Jul 2006 09:26:52 -0300, Mauro Faccenda wrote:
> 
> > > > You see? They cant be the same, because the closing "]" is needed
> > > > by /usr/bin[ and not by /usr/bin/test
> > >
> > > It's quite common for a program to change its behaviour according to
> > > the name used to run it. For example, zcat and gunzip are links to
> > > gzip, yet the three programs behave differently.
> > 
> > but this isn't the case:
> 
> I was disagreeing with the "cant be the same" comment. I know they are
> different files, but the slightly different behaviour is insufficient
> reason for that. Alexander asked why one was not a link to the other, I'd
> like to know too, but this isn't the reason.

For such a simple question, this sure is generating a lot of traffic :-)

The answer is simple:

'test' is a bash builtin. When a bash script executes 'test', it is
not /usr/bin/test that runs, but a function internal to bash.

/usr/bin/test/ is provided for environments that want to run bash
scripts that use test but bash is not the shell in use.

test and [ are not links to each other as they have different syntax
(the closing ]), so they cannot be the same command. If they were
linked, one of them would fail on execution with invalid syntax errors

alan


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Re: [gentoo-user] strange [ file

[Alexander Skwar]

Alan McKinnon wrote:
> On Tue, 2006-07-25 at 14:16 +0100, Neil Bothwick wrote:
>> On Tue, 25 Jul 2006 09:26:52 -0300, Mauro Faccenda wrote:
>> 
>> > > > You see? They cant be the same, because the closing "]" is needed
>> > > > by /usr/bin[ and not by /usr/bin/test
>> > >
>> > > It's quite common for a program to change its behaviour according to
>> > > the name used to run it. For example, zcat and gunzip are links to
>> > > gzip, yet the three programs behave differently.
>> > 
>> > but this isn't the case:
>> 
>> I was disagreeing with the "cant be the same" comment. I know they are
>> different files, but the slightly different behaviour is insufficient
>> reason for that. Alexander asked why one was not a link to the other, I'd
>> like to know too, but this isn't the reason.
> 
> For such a simple question, this sure is generating a lot of traffic :-)
> 
> The answer is simple:
> 
> 'test' is a bash builtin. When a bash script executes 'test', it is
> not /usr/bin/test that runs, but a function internal to bash.

True. Same for [.

> /usr/bin/test/ is provided for environments that want to run bash
> scripts that use test but bash is not the shell in use.

Nothing to argue here.

> test and [ are not links to each other as they have different syntax
> (the closing ]), so they cannot be the same command.

That's not true. /usr/bin/[ and /usr/bin/test *COULD* be the
same commands. If a program is invoked, it gets in $0 the name
the user has used to call the program. Depending on this name/value,
the program could behave differntly.

> If they were
> linked, one of them would fail on execution with invalid syntax errors

Wrong.

Alexander Skwar
-- 
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To ask a politician to lead us is to ask the tail of a dog to lead the dog.
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Re: [gentoo-user] strange [ file

[Alexander Skwar]

Neil Bothwick wrote:
> On Tue, 25 Jul 2006 09:26:52 -0300, Mauro Faccenda wrote:
> 
>> > > You see? They cant be the same, because the closing "]" is needed
>> > > by /usr/bin[ and not by /usr/bin/test
>> >
>> > It's quite common for a program to change its behaviour according to
>> > the name used to run it. For example, zcat and gunzip are links to
>> > gzip, yet the three programs behave differently.
>> 
>> but this isn't the case:
> 
> I was disagreeing with the "cant be the same" comment. I know they are
> different files, but the slightly different behaviour is insufficient
> reason for that. Alexander asked why one was not a link to the other, I'd
> like to know too, but this isn't the reason.

Yes, you're right, [ and test *COULD* be the same command, just like
gzip and gunzip are the same command, but the coreutils makers seem
to have decided otherwise. It's not that important to me, if it were,
I'd ask the coreutils makers and not some 3rd party. :)

Anyway, on other systems (HP-UX, Solaris 8), there isn't even a
/usr/bin/[ - there's just /usr/bin/test.

Alexander Skwar
-- 
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God turn their hearts; and if he doesn't turn their hearts, may
he turn their ankles so we'll know them by their limping.
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Re: [gentoo-user] strange [ file

[Etaoin Shrdlu]

On Tuesday 25 July 2006 15:41, Alan McKinnon wrote:

> The answer is simple:
>
> 'test' is a bash builtin. When a bash script executes 'test', it is
> not /usr/bin/test that runs, but a function internal to bash.
>
> /usr/bin/test/ is provided for environments that want to run bash
> scripts that use test but bash is not the shell in use.

This makes sense.

> test and [ are not links to each other as they have different syntax
> (the closing ]), so they cannot be the same command. If they were
> linked, one of them would fail on execution with invalid syntax errors

This is not 100% true. As Neil Bothwick said, *the same program* can 
behave differently based on the name it was invoked with, so [ could 
very well have been implemented as a link to test (or viceversa), but 
this is not the case, as you can see with a 
ls -l /usr/bin/test /usr/bin/[

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Re: [gentoo-user] strange [ file

[Neil Bothwick]

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On Tue, 25 Jul 2006 15:41:56 +0200, Alan McKinnon wrote:

> The answer is simple:

Maye, but this isn't it.

> 'test' is a bash builtin. When a bash script executes 'test', it is
> not /usr/bin/test that runs, but a function internal to bash.

test and [ are both Bash builtins, but there are also [ and test commands
in /usr/bin. This has nothing to do with the builtins.


> /usr/bin/test/ is provided for environments that want to run bash
> scripts that use test but bash is not the shell in use.

Those scripts can also use /usr/bin/[

> test and [ are not links to each other as they have different syntax
> (the closing ]), so they cannot be the same command. If they were
> linked, one of them would fail on execution with invalid syntax errors

That's wrong, as explained in my previous response that you quoted. A
command receives the name it was invoked with as one of its arguments. So
it is possible for a command to operate differently according to the name
used to run it, such as the gzip/gunzip/zcat example I gave earlier, or
the hundreds of commends in netpbm that are mainly symlinks to a few core
commands.

It's possible to do this with scripts too, I have a number of scripts
that act differently according to the name used to run them.


-- 
Neil Bothwick

Plagarism prohibited. Derive carefully.

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Re: [gentoo-user] strange [ file

[Alan McKinnon]

On Tue, 2006-07-25 at 16:18 +0200, Etaoin Shrdlu wrote:
> > test and [ are not links to each other as they have different syntax
> > (the closing ]), so they cannot be the same command. If they were
> > linked, one of them would fail on execution with invalid syntax
> errors
> 
> This is not 100% true. As Neil Bothwick said, *the same program* can 
> behave differently based on the name it was invoked with, so [ could 
> very well have been implemented as a link to test (or viceversa), but 
> this is not the case, as you can see with a 
> ls -l /usr/bin/test /usr/bin/[ 

Um, no. Read my post again. The command 'test' and the command '[' have
*different* syntax so cannot possible be links to each other and still
have it work. The command does behave differently depending on the name
it is called with, but this does not change the syntax used on the
command line that invokes it.

alan


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Re: [gentoo-user] strange [ file

[Etaoin Shrdlu]

On Tuesday 25 July 2006 15:16, Neil Bothwick wrote:

> I was disagreeing with the "cant be the same" comment. I know they are
> different files, but the slightly different behaviour is insufficient
> reason for that. Alexander asked why one was not a link to the other,
> I'd like to know too, but this isn't the reason.

[slowly getting OT...]

Looking at coreutils sources, it turns out that there are two files: 
test.c and lbracket.c.
test.c is the actual program, and lbracket.c is as follows:

$ cat lbracket.c
#define LBRACKET 1
#include "test.c"

so, test.c does all the work.

After taking a quick look at the code, seems that the only times LBRACKET 
is checked are in the following fragments:


...
/* The official name of this program (e.g., no `g' prefix).  */
#if LBRACKET
# define PROGRAM_NAME "["
#else
# define PROGRAM_NAME "test"
#endif

...

if (LBRACKET)
    {
      /* Recognize --help or --version, but only when invoked in the
   "[" form, and when the last argument is not "]".  POSIX
   allows "[ --help" and "[ --version" to have the usual GNU
   behavior, but it requires "test --help" and "test --version"
   to exit silently with status 1.  */
      if (margc < 2 || !STREQ (margv[margc - 1], "]"))
  {
    parse_long_options (margc, margv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
            usage, AUTHORS, (char const *) NULL);
    test_syntax_error (_("missing `]'\n"), NULL);
  }

      --margc;
    }

  argc = margc;
  pos = 1;
...

Again, the above could have been implemented by looking at argv[0].
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Re: [gentoo-user] strange [ file

[Neil Bothwick]

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On Tue, 25 Jul 2006 16:33:19 +0200, Alan McKinnon wrote:

> Um, no. Read my post again. The command 'test' and the command '[' have
> *different* syntax so cannot possible be links to each other and still
> have it work.

if [ $(basename $0) == "[" ]
then
	#parse for trailing ]
else
	#parse to end of line
fi


-- 
Neil Bothwick

Help! I've fallen and I can't get down! - James Brown

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Re: [gentoo-user] strange [ file

[Etaoin Shrdlu]

On Tuesday 25 July 2006 16:33, Alan McKinnon wrote:

> Um, no. Read my post again. The command 'test' and the command '['
> have *different* syntax so cannot possible be links to each other and
> still have it work. The command does behave differently depending on
> the name it is called with, but this does not change the syntax used
> on the command line that invokes it.

There are two cases:

[1] syntax checking is done by the shell, or
[2] syntax checking is done by the program.

The interesting case is [2]. Let's make an oversimplified example. 
Suppose you want the commands "commandA" and "commandB".
The syntax for commandA is 

commandA <arg1> <arg2>

but commandB takes a third argument, so you invoke it with

commandB <arg1> <arg2> <arg3>

This, to me, qualifies as "*different* syntax".

Here is how those checks can be implemented _using the same program_.


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[]) {

  char *progname;

  /* the following should actually extract the basename of
     the program from argv[0], but to keep things simple 
     let's assume that the shell does this for us */
  progname = argv[0];

  if (strcmp(progname, "commandA") == 0) {

    /* check that we have TWO arguments */
    if (argc == 3) {
      printf("Ok, running as commandA with two arguments\n");
      exit(0);
    } else {
      printf("Running as commandA, but with the wrong number of 
arguments\n");
      exit(1);
    }

  } else if (strcmp(progname, "commandB") == 0) {
    /* check that we have THREE arguments */
    if (argc == 4) {
      printf("Ok, running as commandB with three arguments\n");
      exit(0);
    } else {
      printf("Running as commandB, but with the wrong number of 
arguments\n");
      exit(1);
    }
  } else {
    printf("Bad program name!\n");
    exit(1);
  }
}

In fact, as I said in a previous post, [ and test are built from the same 
source file, and the "[" vs. "test" difference is used only to check for 
proper syntax.
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Re: [gentoo-user] strange [ file

[Alexander Skwar]

Alan McKinnon schrieb:
> On Tue, 2006-07-25 at 16:18 +0200, Etaoin Shrdlu wrote:
>> > test and [ are not links to each other as they have different syntax
>> > (the closing ]), so they cannot be the same command. If they were
>> > linked, one of them would fail on execution with invalid syntax
>> errors
>> 
>> This is not 100% true. As Neil Bothwick said, *the same program* can 
>> behave differently based on the name it was invoked with, so [ could 
>> very well have been implemented as a link to test (or viceversa), but 
>> this is not the case, as you can see with a 
>> ls -l /usr/bin/test /usr/bin/[ 
> 
> Um, no.

Uhm, *YES*.

> Read my post again.

You better do so.

> The command 'test' and the command '[' have
> *different* syntax 

Yes.

> so cannot possible be links to each other 

Why not?

> The command does behave differently depending on the name
> it is called with, but this does not change the syntax used on the
> command line that invokes it.

What are you talking about?

Of course the program could have a different syntax.

For example, compare the syntax that zipinfo and unzip have.

Alexander Skwar
-- 
Delta: The kids will love our inflatable slides.    -- David Letterman
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Re: [gentoo-user] strange [ file

[Daniel da Veiga]

On 7/25/06, Alan McKinnon <alan@linuxholdings.co.za> wrote:
> On Tue, 2006-07-25 at 16:18 +0200, Etaoin Shrdlu wrote:
> > > test and [ are not links to each other as they have different syntax
> > > (the closing ]), so they cannot be the same command. If they were
> > > linked, one of them would fail on execution with invalid syntax
> > errors
> >
> > This is not 100% true. As Neil Bothwick said, *the same program* can
> > behave differently based on the name it was invoked with, so [ could
> > very well have been implemented as a link to test (or viceversa), but
> > this is not the case, as you can see with a
> > ls -l /usr/bin/test /usr/bin/[
>
> Um, no. Read my post again. The command 'test' and the command '[' have
> *different* syntax so cannot possible be links to each other and still
> have it work. The command does behave differently depending on the name
> it is called with, but this does not change the syntax used on the
> command line that invokes it.
>

Why not? The syntax is simply based on tests performed over the
arguments received, the name of the program is one of those arguments,
what stop the programmer to test the name and change the syntax
accourding with that name? Many of my scripts behave differently
accourding with the name it was called. That allows me to write simple
tests, symlink the same program to different names and have different
behavior/syntax, much better than copy the same file and edit it.

-- 
Daniel da Veiga
Computer Operator - RS - Brazil
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