Hi Ranjan,
Ranjan Maitra wrote:
> On Tue, 20 Oct 2020 18:11:23 -0500 Ranjan Maitra
> <maitra@xxxxxxxxx> wrote:
>
>> Thanks, everybody, I am almost there. I am wondering how
>> do I get to list the files without the first two depths?
>> So, here is a part of my code:
>>
>> MAILDIR=$HOME/Maildir
>> MHDIR=$HOME/mail
>> FOLDERSPre=$(find $MHDIR -type d -mindepth 1)
>>
>> So, then I get a list of directories:
>> /home/username/mail/....
>>
>> How do I get the /home/username out of it so that I can
>> append the rest to my Maildir directory?
>>
>> I guess this is now likely a bash question, and well and
>> truly OT. Luckily, every part of this thread is.
>
> Sorry to answer my own question, but I managed to do this
> by using sed.
Nothing to be sorry about there. You've answered your own
question, but also shared it with the list where others can
learn from it. That's always a plus!
> I used:
>
> for ff in $FOLDERSPre
>
> f=$(echo "$ff" | sed -e 's/mail/Maildir/')
>
> which is easier than what i was trying to do: remove the /home/username/mail out and replace with /home/username/Maildir.
Another way to slice this would be through parameter
expansion. For example:
for ff in $FOLDERSPre; do
f=${ff/$MHDIR/$MAILDIR}
...
done
In the bash manual, search for "Parameter Expansion" for
details on the various types of expansions available. While
the speed of a parameter expansion versus a command
substitution (i.e., the $(echo $ff | sed ... ) in your
example) isn't likely to be noticeable in a script doing a
large MH to Maildir conversion, there are times when it can
improve a script's speed and/or system utilization.
Even without the small performance boost, using a parameter
expansion is often more concise and removes an external
command from the script.
The trade off is that if you're writing a script which needs
to be portable across a wide variety of different operating
systems, you need to consider whether you're using an
expansion that's supported by any POSIX shell (e.g. sh) or
is bash-specific (and ideally adjust the code and/or the
"#!" hashbang appropriately).
Of course, writing such scripts also involves knowing the
same of the utilities like sed, which can vary a good bit
between a GNU/Linux system, BSD-derivatives, Solaris, etc.
--
Todd
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