sed -i "/Comment=/c\ ${comment}" "${launcher}"

Hi Rainer et al,

Using the above command results in replacing lines containing
"Comment=" by the value of launcher plus one leading space. The weird
thing is that I found that if I remove the space between
"/Comment=/c\" and "${comment}", the line will be replaced by the text
"${Comment}". I am attributing this to a possible shell bug.

How do you explain such behaviour?

Edward

On 07/01/2016, Edward Bartolo <edbarx@???> wrote:
> Hi Rainer, Aitor and All,
>
> I edited the netman-gui.postinst shell code to create a link instead
> of having two identical launchers in different locations as suggested
> by Rainer. The latest sources are already pushed to git.devuan.org.
>
> Edward
>
> On 06/01/2016, Edward Bartolo <edbarx@???> wrote:
>> Hi Rainer, Aitor and All,
>>
>> netman-gui.postinst now is debugged to behave properly when
>> dpkg-reconfigure is used on netman-gui.
>>
>> sed is still adding an unneccessary leading space in lines Exec= and
>> Comment= in both .desktop files.
>>
>> I was suggested to drop one of the .desktop files and use a symlink
>> instead. I think this is a good idea, but I have been coding for 10
>> hours 30 minutes now, so it is time for me to go to sleep.
>>
>> Edward
>>
>> On 06/01/2016, Rainer Weikusat <rainerweikusat@???> wrote:
>>> Edward Bartolo <edbarx@???> writes:
>>>> Enjoy yourself, I am working on it. I think, I got a way of putting it
>>>> right. There are two .desktop files that control how netman gui
>>>> behaves:
>>>> a) /etc/xdg/autostart/netman.desktop
>>>> b) /usr/share/applications/netman.desktop
>>>>
>>>> The netman-gui.postinst script has to modify both of them.
>>>
>>> In this case, you shouldn't copy the file but create a symlink to
>>> it. This means there's only one copy which has to be modified.
>>>
>>> [...]
>>>
>>>> The sed command in the postinst script also has to
>>>> make sure no multiple Exec= and Comment= lines are added to both
>>>> .desktop files.
>>>
>>> sed is generally the wrong choice for editing files (as it's the 'stream
>>> editor'). ed can be used for that (needs to become a package dependency
>>> as 'certain people in the Debian project' were hit by a pine at a
>>> formative age and are thus opposed to using sensibly-working text
>>> editors).
>>>
>>> The following shell function should be sufficient for your use-case
>>>

>>> -------
>>> change_line()
>>> {
>>>     file="$1"
>>>     new="`echo $2 | sed 's/\(.\)/\\\\\1/g'`"
>>>     key=`expr "$2" : "\([^=]\+=\)."`
>>>     ed "$file" <<EOF
>>> /^$key/s/.*/$new
>>> wq
>>> EOF
>>> }
>>> -------

>>>
>>> This takes a file as first argument and the new line as second
>>> argument. If a line with the same 'keyword' (text before the first =)
>>> already exists, it's replaced. Otherwise, nothing happens.
>>>
>>> NB: Like all shell code (or most), this won't work with 'suitably
>>> crafted input'. But shell programming is an exercise in inventing 'good
>>> enough' solutions for fairly well-defined problems.
>>> _______________________________________________
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>>>
>>
>