[sf-lug] > and >> and < and << and |

[jim]

$ echo $SHLVL
1
$ which dash
/bin/dash
$ dash
$ echo $SHLVL
2
$

## the  SHLVL  environment variable has an integer
## that reflects the current parent-child level
## of the shell in which one invokes the command.
## the prompt does not reveal exactly what shell
## is running, although the  $  prompt lets us
## assume its a Bourne family shell.
## The  dash  command (the which command searches
## the PATH environment variable value and
## verifies that  dash  is invokable). The value
## of the  SHLVL  environment variable shows the
## current shell has a parent.

     My first reason for using the  dash  shell is
its man page, which is crystal clear and a great
way for someone to learn how to use any shell.
The man page is clear partly because the design
of the  dash  shell is simple, no kitchen sinks.
     The  dash  shell features are all I need,
the exotic features of the  bash  shell give me
a headache, so why use that elephant gun to
shoot my jack rabbits. Much smaller memory
requirement, pretty much bug free, with docs
that I can readily peruse all the times I forget
stuff.


On 08/09/2016 01:29 AM, Alex Kleider wrote:
> On 2016-08-08 10:32, jim wrote:
>
>> (The DASH man page is glorious, unlike some other
>> man pages.)
>
> I've noticed that some small (SoC) systems come with dash rather than 
> bash and assumed that the former was a 'smaller' version of the latter 
> and was surprised that my system (current LTS of Ubuntu) seems to have 
> both installed.
> $ man DASH  # man page
> $ man dash  # same man page
> $ man bash  # different structure but I find no differences in 
> behaviour described.
> $ dash # => a '$' prompt by itself; I'm in another shell, dash this time.
> $ DASH
> DASH: command not found
> $ bash  # a pause and then the same prompt returns; I'm in another shell.
>
> interesting.
> Under what circumstances would someone with both installed wish to use 
> dash rather than bash?
>
> Alex
>