General admin questions
2007-12-25 11:50:00
was well deserved. Temporary Insanity.
> 1. What is the difference between at(1) and crontab(1)? Is at(1) really
> used anymore? If so, for what?
at: executes a job at a time in the future.
cron: executes a job at a given time, regularly (repeatedly).
Usually, batch(1) runs jobs when load is below a set number, and at(1)
runs them at a set time regardless of load.
A user's crontab contains the times and commands for cron. Root's crontab
usually contains 'atrun' which checks at's queue to see if any users have
one-time jobs to run, as well.
> 2. How can export shell functions? I'd like to call one shell script from
> another, and have the functions that I defined in the first function to
> automatically be available in the second shell script. Specifically, I'd be
> working with ksh and sh. Is this possible?
I really was already aware of the answer I received. Basically, source
the file before trying to use it. I really thought there was a way
to export it using 'typeset' without having to resource it each time, but
apparently it's very shell-specific, which I haven't entirely figured out
yet. The best response includes:
It depends on what you mean by "call". you can source the contents
and it will be read into the same subshell, its statements executed,
and its functions made available:
#!/bin/sh
. /path/to/other/script.sh
the space is important
> 3. I'd like the backspace key to function as backspace, and the delete
> key to delete characters to the right of the cursor. So, I used
> 'stty erase ^H' (where ^H is produced by pressing the backspace key).
> Now it seems the backspace works, but delete sometimes produces a ^?
> instead.
Responses included a pointer to the Linux Backspace FAQ available at:
ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Keyboard-and-Console-HOWTO
Other responses included using "set -o vi" which will allow you to use vi
commands to edit on the command line. Many of my users are from the PC
world, and hardly understand vi, which is why I haven't done it this way.
This question really brought up another annoying question I have had for
a while. That is, what is the difference between /sbin/sh and /bin/sh?
Is /sbin/sh statically linked, while /bin/sh is not? Has anyone dared
converting their root login shell to bash? Perhaps a static bash exists?
The most concise response came from R A Lichtensteiger <rali@meitca.com>
who wrote:
I use xmodmap(1) to remap the Backspace key to emit the same "key code" as
Delete, then use stty to set them to erase:
% grep Delete .Xmodmap
! Now we want the Back Space key to emit the "Delete" keysym
keycode 50 = Delete
% grep .Xmodmap .xinitrc
xmodmap $HOME/.Xmodmap
% grep stty .cshrc
stty intr "^C"
stty erase "^?"
I'm doing this using straight X11R6, not Openwin, so your filenames may
be different ... This setup works fine for most things -- it gets a
little wierd when doing remote login from a Linux box's console (the keys
don't get remapped!).
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