Steve Bennett's questions

When downloading a large file, there is a big discrepancy beween the actual file size (which I care about) and the allocated (ie, final) size (which I usually don't.)

$ ls -lshk
9962420 -rw-r--r--  1 stevebennett  staff    19G 16 Jan 14:30 parcelsclip.zip_.gstmp

In this case, the file will be 19GB eventually, but right now, it's only 9.96GB, as indicated by the first column.

Is there a way to have that 19G column show the current size (9962420), but in human-friendly terms (10GB)?

I need the psql command line tools, but I don't need the actual Postgres RDBMS. This is to work with a package which supports a psql interface.

Is it possible to install just psql?

(Ubuntu 16.04)

I've been through quite a few rounds of this over the years:

1. Someone gives me their id_rsa.pub
2. I copy it into .ssh/authorized_keys
3. I ask them to test
4. Some time later, they test and report it doesn't work.
5. I mess around with line feeds, permissions etc, go back to step 3.

Is there any way (obviously without asking for their private key) to verify that a public key has been installed correctly?

I'm trying to install an extension for GeoServer. The instructions say:

Create a GDAL_DATA environment variable to the folder where you have extracted this file. Make also sure that this directory is reachable and readable by the application server process’s user.

and later (for a different file):

If you are on Linux, be sure to set the LD_LIBRARY_PATH environment variable to refer to the folder where the SOs are extracted.

I'm not sure where to set these variables. In /etc/init.d/tomcat7 perhaps?

From man apt-get:

Note that quiet level 2 implies -y; you should never use -qq without a no-action modifier such as -d, --print-uris or -s as APT may decide to do something you did not expect.

Those options all, as suggested, don't actually install anything. What's wrong with using -qq as a quieter alternative to -y ?

From the man page:

-m, --ignore-missing, --fix-missing
  Ignore missing packages; if packages cannot be retrieved or fail the integrity 
  check after retrieval (corrupted package files), hold back those packages and 
  handle the result. 

  Use of this option together with -f may produce an error in some situations. If a 
  package is selected for installation (particularly if it is mentioned on the 
  command line) and it could not be downloaded then it will be silently held back. 

 Configuration Item: APT::Get::Fix-Missing.

This is confusing:

1. How can 'ignore missing' and 'fix missing' be synonyms for the same option?
2. What does 'hold back' mean in this context?
3. What does 'handle the result' mean?

And in what situation is it useful anyway? When you try to install a package not in the apt index, you get this message:

E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

Are the two suggestions (apt-get update, apt-get install --fix-missing...) at all equivalent?

This is slightly messy to explain.

I have a script that I want to deploy like this:

curl -Ls example.com/myscript.sh | bash

The trouble is the script reads from standard input like so:

echo "You should edit /srv/pillar/tm.sls now. Comments are in the file."
echo Type "skip" to skip or anything else to edit.
read text
if [ "$text" != "skip" ]; then
sudo pico /srv/pillar/tm.sls
fi

Now, since stdin is obviously serving as the source of the script itself, this doesn't currently work. Is there a way I can regain the terminal?

(The current workaround is to deploy it like this: curl -Ls example.com/myscript.sh > myscript.sh && bash myscript.sh)

I want to execute a script, start.sh on a remote server which runs this:

nohup node server.js &

Naively, I call SSH like this:

ssh myserver <<EOF
./start.sh &
EOF

This starts the script, but leaves the session connected. I want to follow this step with other commands in a script, so that's no good.

How can I SSH to the remote machine, launch a nohup command into the background, then disconnect? I suppose I could put the SSH process itself into the background, but that doesn't seem right.

What's a simple way to run a command, say, 8 hours from now? I can think of this way:

nohup bash -c "sleep 28800 ; ./mycommand.sh" &

Is there a more "proper" way?

On my server, these both return the host name:

$ ubuntu@mt-solo:~$ uname -n
myserver
$ ubuntu@mt-solo:~$ hostname
myserver

Is this always the case?

I have a server which exists to run one little Django application. If the server reboots, I want Django to start again:

nohup /opt/myapp/manage.py runserver ...

I'm having trouble finding a simple way to make this run. There are tutorials explaining how to write full-fledged services, runlevels, init.d etc. But there must be a simpler way? A place where I can hack this one extra line onto?

EDIT Mark's answer is perfect, the one-liner works out as:

sudo sed --in-place '/^exit 0/i\cd /opt/appdir\npython manage.py runserver .... &' /etc/rc.local