Re: newline in IOCSH_PS1 value

[Mark Davis <davism50@msu.edu>]

I was starting to come to the same conclusion:  That there was something fundamentally wrong in some basic assumption I was making that I didn't even know I was making it.

The culprit turned out to be the sudo command.

Experimenting with the various nested scripts we use to launch the IOC shell, I found that, indeed, setting the IOCSH_PS1 value in any one of them worked just fine, so it had to be something about how I was launching the outermost one, since it was completely ignoring the value I set in my login shell.

The problem turned out to be that I was launching the scripts using sudo, and the default behavior for sudo is to NOT execute commands using your existing environment.  This make sense from a security standpoint, but I had somehow never run in to the issue before or given it any thought.  To pass my test the way I was doing it, all I needed was to use the -E option on the sudo command.

Of course, that was only for testing.  For normal use, I will have one of the scripts set the value.  But at least now I know about this (perfectly sensible) behavior and (hopefully) won't bang my head on that particular wall again.

I never know what new tidbit I am going to learn when I launch in to one of these "quick" projects (I mean, really, all I wanted to do was change the shell prompt!  How hard could THAT be?  ARRrrgggghhhhhh!)

Anyway, thanks for your help, and in helping to get me pointed in the right direction.

Mark Davis


On 2/27/2014 11:25 AM, Eric Norum wrote:

You’re trying this on linux? 

I just tried:

makeBaseApp.pl -t example example

makeBaseApp.pl -t example -i example

make

cd iocBoot/iocexample/

../../bin/linux-x86_64/example st.cmd

export IOCSH_PS1=“FOO

BAR> "

../../bin/linux-x86_64/example st.cmd

and got

. . .

## Start any sequence programs

#seq sncExample, "user=enorumHost"

FOO

BAR> 

I didn’t type anything fancy on the export line — just a <return>.

I then added this line to the startup script:

epicsEnvSet IOCSH_PS1 "$(PROMPT)"

and

export PROMPT="ONE LINER> "

../../bin/linux-x86_64/example st.cmd

. . .

## Start any sequence programs

#seq sncExample, "user=enorumHost"

ONE LINER> 

export PROMPT="TWO

> LINER> "

../../bin/linux-x86_64/example st.cmd

. . .

## Start any sequence programs

#seq sncExample, "user=enorumHost"

TWO

LINER> 

The fact that you get a complaint about PROMPT being undefined makes me think that there’s something weird with your linux shell — that it’s not actually passing on the environment properly.

On Feb 27, 2014, at 8:03 AM, Mark Davis <davism50@msu.edu> wrote:

Don't know why it doesn't work for for me.

I tried this first just using the name IOCSH_PS1 for my bash environment variable, which didn't work.

Figuring that the IOCSH_PS1 value might get some special treatment, or that something in the scripts we use to lauch the IOC shell are doing something of their own, I tried this:

___________________________________________
In my bash shell, before launching the IOC shell:

davis-pc:/home/epics/R3.14.12.2/apps/mdlinux/iocBoot/iocFrib> export PROMPT=$'\nmdlinux> '

  OR

davis-pc:/home/epics/R3.14.12.2/apps/mdlinux/iocBoot/iocFrib> export PROMPT="    <--- typed Ctl+V, Ctl+J
mdlinux> "

___________________________________________
Both of which produce the same effect: 

davis-pc:/home/epics/R3.14.12.2/apps/mdlinux/iocBoot/iocFrib> env

...
PROMPT=
mdlinux>
...

   OR

davis-pc:/home/epics/R3.14.12.2/apps/mdlinux/iocBoot/iocFrib> set | grep PROMPT
PROMPT=$'\nmdlinux> '

___________________________________________
In the st.cmd file:

epicsEnvSet("IOCSH_PS1", "$(PROMPT)")

   which produces the error:

macLib: macro PROMPT is undefined (expanding string epicsEnvSet("IOCSH_PS1", "$(PROMPT)"))

  and I also tried:

epicsEnvSet IOCSH_PS1 $(PROMPT)

    which produces the error:

macLib: macro PROMPT is undefined (expanding string epicsEnvSet IOCSH_PS1 $(PROMPT))
___________________________________________

Is there something special you have to do to get a particular bash environment variable to show up in the EPICS IOC shell?  If not, what determines which ones show up and which ones don't?

Mark Davis

-- 
Eric Norum
eric@norum.ca