what is the difference between these two symbol

ust · 05-12-2011, 12:33 AM

1) .
2) -.

I know the first symbol means current , what is the meaning of the second symbol ?

Thanks.

chrism01 · 05-12-2011, 01:01 AM

Be nice if you specified the context there. but I assume(!) you mean dirs, in which case

Code:

'.' = current dir
'..' = parent dir
'-' = dir you were prev in

#NB you can 'cd' to all, but the first would be pointless

Here's hoping that wasn't a homework qn ....
In any case, try these
http://rute.2038bug.com/index.html.gz
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/

ust · 05-12-2011, 02:03 AM

the reply ,

This is not homework , I am doing server admin task for a database server .

sorry , I am not too understand the use of '-.' , - mean previous path , what is the mean of -. ?

for example , I set PATH=-.:$PATH , what is -. mean ?

markush · 05-12-2011, 02:36 AM

Hi,

which Shell are you using?

if you want to search for "-." in a manpage, you may use the searchcommand

Code:

/-\.

, both bash and ksh have some builtin functions which use this expression.

Markus

ust · 05-12-2011, 07:59 PM

Quote:

Originally Posted by markush

Hi,

which Shell are you using?

if you want to search for "-." in a manpage, you may use the searchcommand

Code:

/-\.

, both bash and ksh have some builtin functions which use this expression.

Markus

I use bash .

Tinkster · 05-12-2011, 09:14 PM

That would mean someone was stupid enough to create a directory
with the name '-.' and added it to the PATH.

markush · 05-13-2011, 01:59 AM

There are (at least) two sections in the Bash-manpage where '-.' is mentioned (but not according to pathes).

Markus

Tinkster · 05-13-2011, 05:37 PM

Quote:

Originally Posted by markush

There are (at least) two sections in the Bash-manpage where '-.' is mentioned (but not according to pathes).

Markus

Which version of bash is that?
GNU bash, version 3.1.17 has a few occurrences of the string '-.'.

But a quick glance will show that the period is only punctuation
terminating the sentence talking about the hyphen.

Cheers,
Tink

markush · 05-13-2011, 05:49 PM

Quote:

Originally Posted by Tinkster

Which version of bash is that?
GNU bash, version 3.1.17 has a few occurrences of the string '-.'.

Code:

markus@samsung:~$ bash --version
GNU bash, version 4.1.10(2)-release (x86_64-slackware-linux-gnu)
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
markus@samsung:~$

Quote:

But a quick glance will show that the period is only punctuation
terminating the sentence talking about the hyphen.
...

Here the sections of the manpage

Code:

yank-last-arg (M-., M-_)
              Insert  the  last  argument  to  the  previous  command (the last word of the previous history
              entry).   With  an  argument,  behave  exactly  like  yank-nth-arg.    Successive   calls   to
              yank-last-arg  move back through the history list, inserting the last argument of each line in
              turn.  The history expansion facilities are used to extract the last argument, as if the  "!$"
              history expansion had been specified.

and

Code:

 insert-last-argument (M-., M-_)
              A synonym for yank-last-arg.

I don't think that the '.' is punctuation in these cases.

Markus

Tinkster · 05-13-2011, 11:08 PM

Quote:

Originally Posted by markush

Code:

markus@samsung:~$ bash --version
GNU bash, version 4.1.10(2)-release (x86_64-slackware-linux-gnu)
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
markus@samsung:~$

Here the sections of the manpage

Code:

yank-last-arg (M-., M-_)
              Insert  the  last  argument  to  the  previous  command (the last word of the previous history
              entry).   With  an  argument,  behave  exactly  like  yank-nth-arg.    Successive   calls   to
              yank-last-arg  move back through the history list, inserting the last argument of each line in
              turn.  The history expansion facilities are used to extract the last argument, as if the  "!$"
              history expansion had been specified.

and

Code:

 insert-last-argument (M-., M-_)
              A synonym for yank-last-arg.

I don't think that the '.' is punctuation in these cases.

Markus

No, it's not, but "M-.", in other words "press&hold Alt, then ." has
a completely different meaning from a textual "-." . Those are emcas-
like keybindings.

Cheers,
Tink

markush · 05-14-2011, 02:19 AM

thanks for the clarification, I was wondering what this charactes do and didn't understand it. I did not understand that it are keybindings (well, I didn't use Emacs since the year of 1996

)

But now it is clear that in the Bash-manpage there is no "-." mentioned and same thing for ksh.

Markus