Re: using less in a bash script, screen blanking, alternate screen

[Zenaan Harkness <zen@freedbms.net>]

On 9/8/13, Zenaan Harkness <zen@freedbms.net> wrote:
> On 9/8/13, Zenaan Harkness <zen@freedbms.net> wrote:
>> OK, I have the following script (reduced, just enough to demonstrate
>> the problem):
>>
>> --- test.sh ---
>> #!/bin/bash
>> cmd="apt-cache search debian-installer | sort | egrep --color=always
>> -i debian-installer"
>> #tput nrrmc # line 3
>> #less -REf <($cmd) # line 4
>> less -REf <(bash -c "$cmd") # line 5
>> #less -REf <(tput nrrmc; bash -c "$cmd") # line 6
>> #less -REf <(bash -c "tput nrrmc; $cmd") # line 7
>> ---
>>
>> I am running this script in a plan xterm (no embedded screen session),
>> bash shell.
>>
>> When I manually run lines 2 then 5 in xterm, I get expected output in
>> my terminal.
>>
>> When I run test.sh from xterm, I get a blank screen, followed by
>> return to the xterm, as though the script didn't do anything! I would
>> like to understand why.
>
> Solution is use -X (--no-init) option to less.

Thank you Sven for this -X solution (you sent this solution at the
same time about that I drafted and sent my same finding).

>> Commenting out line 5, and
>
>> ... uncommenting line 4 gives an error, since the command is
>> being substituted as though it is a single command, instead of a
>> pipeline. I am wondering how I might fix this particular problem
>> without using a full bash instantiation as seen in line 5 - line 7.
>
> I am still interested in whether there is some command-substitution
> alternative in bash, which can properly interpret pipe ("|")
> character, to save the launching of a full sub-shell...

This I finally found too, just this arvo - "eval" bash builtin command!

Thanks again
Zenaan