[TriLUG] Single line scripts

[Brian Gerard via TriLUG]

On 09/05/2016 03:34 PM, Grawburg via TriLUG wrote:
 >
 > I have long commands I enter in a terminal, such as starting
 > connecting to a Raspberry Pi located several floors away with ssh, or
 > setting up a connection to my NAS (rather than having a line in
 > /etc/fstab).
 > I can simply have a text file saved and do a copy and paste into
 > terminal each time I need it, but I'd like to turn it into a what I
 > would have called a .bat file decades ago.
 > Is this something I should learn to to do in bash? I don't need
 > multiple lines, there is no extra coding, just a single line.
 >
 > Thanks,
 > Brian Grawburg

Going by your description, I would second the recommendation for aliases
or functions.  The decision between them will more or less come down to
whether or not you need to pass arguments to the commands.

For example...

#
# Use an alias if the command is exactly the same every time.
#
bash$ alias dfhome='ssh -q my-home-machine "df -h"'
bash$ dfhome
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       312G  112G  185G  38% /
tmpfs           385M  896K  384M   1% /run
/dev/sda2        30G  179M   28G   1% /tmp
/dev/sda3       184G   65G  110G  38% /home

#
# Or a function if you want to be able to change behavior.
#
bash$ function dfon() { ssh -q $1 "df -h"'; }
bash$ dfon my-home-machine
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       312G  112G  185G  38% /
tmpfs           385M  896K  384M   1% /run
/dev/sda2        30G  179M   28G   1% /tmp
/dev/sda3       184G   65G  110G  38% /home
bash$ dfon some-other-machine
# ...etc...

Try it, tweak it, repeat.   Once you've got it where you want it, add it
to your .bashrc and you'll have it whenever you log in.

A shell script in your own ~/bin directory or the like is absolutely
fine as well, but sounds a trifle heavy for what you've described.
However, I would say the opposite if these are things you'll need to ssh
in and run without starting up a login shell (like 'ssh my-host
"one-of-these-commands"').  In that case you will want a separate shell
script rather than aliases or functions in your .bashrc.

I covered some of this in the "bash tips n tricks" talk I gave a couple
of years back.  You can find the materials for that at:
https://github.com/briangerard/bash_class
(the section on aliases begins on slide 32, and functions begin on
slide 38)

...and the recording is viewable here:
https://www.youtube.com/watch?v=J4_tFm4iRpc

HTH-
Brian