On Tue, May 17, 2011 at 11:11:58AM -0400, Robert Jim Fulner wrote:
Your script is a little beyond my understanding. Would you mind taking
some time to explain what's actually going on here?
Sorry for the delay; I wrote line by line explanations (maybe more than
you wished), and since this allowed me to think again about it I wrote
an improved version of the script.
#!/bin/sh
This must be the first line (and there must be no space before #!) and means
that when you execute the script (the file must be executable), the content
will
be interpreted by the shell /bin/sh (this is linked to dash for me).
if elinks -remote ping\(\) 2/dev/null; then
elinks -remote ping\(\) returns true if ELinks is running. It's necessary to
escape the parentheses with \ (writing ping() with double quotes would also
work) otherwise the shell interprets ping() as the start of a function
definition.
2/dev/null means that the error output of this command is discarded, so
that if ELinks is not running you won't see the error message it
displays:
ELinks: No running ELinks found.
exec elinks -remote ${1:-about:blank}
If an ELinks instance was found, run the command
elinks -remote ${1:-about:blank}
${1:-about:blank} means:
- $1, i.e. the first parameter of the script if there was one;
- about:blank by default, you can replace it with whatever URL you like.
So if a URL was passed as a parameter it is opened in a new tab,
otherwise a new tab with the URL about:blank is opened ('elinks -remote' alone
returns an error).
elif [ -n $DISPLAY ]; then
[ -n $DISPLAY ] is the same as test -n $DISPLAY and returns true if the
DISPLAY environment variable is set, which means that an X server is available.
exec roxterm -p ELinks -e elinks $1
In that case, execute
roxterm -p ELinks -e elinks $1
Which means launch a new roxterm window with the profile ELinks, and
execute the command 'elinks $1' in this window.
As above $1 is the first parameter given to the script, I didn't set
a default parameter in case $1 is empty because 'elinks' with no
parameter doesn't return an error.
You should replace roxterm -p ELinks with the terminal emulator and
options you want to use. The option -e is standard for all terminal
emulators and allows to run a command in the new terminal, but with some
terminal emulators it's necessary to write
... -e elinks $1
because they interpret only the argument of the option as the command to
run, while most emulators interpret everything until the end of the line
as the command.
else
elinks $1
fi
If neither ELinks nor X is running we are in a Linux console, just run elinks
with the given URL. If you don't care about this case you can remove it
and replace elif ... then with else.
exit 0
Return 0 (no error) when finishing the script, but I think this line
should be removed, because it hides the error code possibly returned by
one of the previous commands (and anyway with the exec's this line is
not even read).
The exec at the beginning of the lines mean that the command following
replaces the shell. Actually I don't see any difference when I remove
them, but since the aim of the script is to launch another program
I think it's better to keep them (and add one in the third case).
A thing that is missing from the script is an at the end of the line with
the terminal emulator, in order to run the command in the background (this
changes nothing for roxterm and some others, but is useful with e.g. xterm if
you run the script from a terminal).
It's also possible to use variables to set your preferences, so here is
an improved version, with xterm as a terminal emulator:
#!/bin/sh
DEFAULT_URL=about:blank
TERMINAL=xterm
if elinks -remote ping\(\) 2/dev/null; then
exec elinks -remote ${1:-$DEFAULT_URL}
elif [ -n $DISPLAY ]; then
exec $TERMINAL -e elinks $1
# If you get an error or if the URL is ignored with your
# TERMINAL setting, comment the line above and use the
following
# instead:
#exec $TERMINAL -e elinks $1
else
exec elinks $1
fi
Or more simply, if you don't care about the no X display case:
#!/bin/sh
DEFAULT_URL=about:blank
TERMINAL=xterm
if elinks -remote ping\(\) 2/dev/null; then
exec elinks -remote ${1:-$DEFAULT_URL}
else
exec $TERMINAL -e elinks $1
# If you get an error or if the URL is ignored with your
# TERMINAL setting, comment the line above and use the
following
# instead:
#exec $TERMINAL -e elinks $1
fi
When I wrote the first version of this script a few years ago I intended
to send a patch with something like that to include it in the
documentation of ELinks (there is already
