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Edit your /etc/syslog.conf, and put in the following line:
# Dump everything on tty8
*.* /dev/tty8
One caveat: REMEMBER TO USE TABS! syslog doesn't like spaces...
From a newbie to another, here is a short script that eases looking for
and viewing howto documents.
My howto's are in /usr/doc/faq/howto/ and are gzipped. The file names are
XXX-HOWTO.gz, XXX being the subject.
I created the following script called "howto" in the /usr/local/sbin
directory:
#!/bin/sh
if [ "$1" = "" ]; then
ls /usr/doc/faq/howto | less
else
gunzip -c /usr/doc/faq/howto/$1-HOWTO.gz | less
fi
When called without argument, it displays a directory of the available
howto's. Then when entered with the first part of the file name (before
the hyphen) as an argument, it unzips (keeping the original intact) then
displays the document.
For instance, to view the Serial-HOWTO.gz document, enter:
$ howto Serial
Here comes a short script which will check from time to time
that there is enough free space available on anything
which shows up in mount (disks, cdrom, floppy...)
If space runs out, a message is printed every X seconds
to the screen and 1 mail message per filled device is fired up.
#!/bin/sh
#
# $Id: check_hdspace,v 1.18 1996/12/11 22:33:29 root Exp root $
#
#
# Since I got mysterious error messages during compile when
# tmp files filled up my disks, I wrote this to get a warning
# before disks are full.
#
# If this stuff saved your servers from exploding,
# send praising email to zocki@goldfish.cube.net.
# If your site burns down because of this, sorry but I
# warned you: no comps.
# If you really know how to handle sed, please forgive me :)
#
#
# Shoot and forget: Put 'check_hdspace &' in rc.local.
# Checks for free space on devices every $SLEEPTIME sec.
# You even might check your floppies or tape drives. :)
# If free space is below $MINFREE (kb), it will echo a warning
# and send one mail for each triggering device to $MAIL_TO_ME.
# If there is more free space than trigger limit again,
# mail action is also armed again.
#
# TODO: Different $MINFREE for each device.
# Free /*tmp dirs securely from old junk stuff if no more free space.
DEVICES='/dev/sda2 /dev/sda8 /dev/sda9' # device; your put disks here
MINFREE=20480 # kb; below this do warning
SLEEPTIME=10 # sec; sleep between checks
MAIL_TO_ME='root@localhost' # fool; to whom mail warning
# ------- no changes needed below this line (hopefully :) -------
MINMB=0
ISFREE=0
MAILED=""
let MINMB=$MINFREE/1024 # yep, we are strict :)
while [ 1 ]; do
DF="`/bin/df`"
for DEVICE in $DEVICES ; do
ISFREE=`echo $DF | sed s#.\*$DEVICE" "\*[0-9]\*""\*[0-9]\*" "\*## | sed s#" ".\*##`
if [ $ISFREE -le $MINFREE ] ; then
let ISMB=$ISFREE/1024
echo "WARNING: $DEVICE only $ISMB mb free." >&2
#echo "more stuff here" >&2
echo -e "\a\a\a\a"
if [ -z "`echo $MAILED | grep -w $DEVICE`" ] ; then
echo "WARNING: $DEVICE only $ISMB mb free. (Trigger is set to $MINMB mb)" \
| mail -s "WARNING: $DEVICE only $ISMB mb free!" $MAIL_TO_ME
MAILEDH="$MAILED $DEVICE"
MAILED=$MAILEDH
# put further action here like cleaning
# up */tmp dirs...
fi
elif [ -n "`echo $MAILED | grep -w $DEVICE`" ] ; then
# Remove mailed marker if enough disk space
# again. So we are ready for new mailing action.
MAILEDH="`echo $MAILED | sed s#$DEVICE##`"
MAILED=$MAILEDH
fi
done
sleep $SLEEPTIME
done
If you're like me, you have a list with 430 subscribers, plus 100+ messages per day coming in over UUCP.
Well, what's a hacker to do with these huge logs?
Install chklogs, that's what.
Chklogs is written by Emilio Grimaldo, grimaldo@panama.iaehv.nl, and the current version 1.8
available from ftp.iaehv.nl:/pub/users/grimaldo/chklogs-1.8.tar.gz.
It's pretty self explanatory to install(you will, of course, check out the info in the doc subdirectory).
Once you've got it installed, add a crontab entry like this:
# Run chklogs at 9:00PM daily.
00 21 * * * /usr/local/sbin/chklogs -m
While you're at it, mention to the author how nice a peice of software this is:)
Create a file called rmcores(the author calls it handle-cores) with the
following in it:
#!/bin/sh
USAGE="$0 <directory> <message-file>"
if [ $# != 2 ] ; then
echo $USAGE
exit
fi
echo Deleting...
find $1 -name core -atime 7 -print -type f -exec rm {} \;
echo e-mailing
for name in `find $1 -name core -exec ls -l {} \; | cut -c16-24`
do
echo $name
cat $2 | mail $name
done
And have a cron job run it every so often.
Quick way to move an entire tree of files from one disk to another
(cd /source/directory && tar cf - . ) | (cd /dest/directory && tar xvfp -)
[ Change from cd /source/directory; tar....etc. to prevent possibility of trashing directory in case of disaster.
Thanks to Jim Dennis, jim@starshine.org, for letting me know. -Maint. ]
Ever wondered which directories are the biggest on your computer? Here's how to find out.
du -S | sort -n
Kudos go to John Fisk, creator of the Linux Gazette. This is an excellent
e-zine plus, it's FREE!!! Now what more could you ask? Check it out at:
http://www.linuxgazette.com
BTW, It turns out that (1) LG is now out on a monthly basis, and (2) John Fisk no longer maintains it, the fellows at SSC do.
I don't know if many people have this problem, but there is a "feature" of GNU
make version 3.70 that I don't like. It is that VPATH acts funny if you give it
an absolute pathname. There is an extremely solid patch that fixes this, which
you can get from Paul D. Smith <psmith@wellfleet.com>. He also posts the
documentation and patch after every revision of GNU make on the newsgroup
"gnu.utils.bug" Generally, I apply this patch and recompile gmake on every
system I have access to.
Q: How do I stop e2fsck from checking my disk every time I boot up.
A: When you rebuild the kernel, the filesystem is marked as 'dirty' and
so your disk will be checked with each boot. The fix is to run:
rdev -R /zImage 1
This fixes the kernel so that it is no longer convinced that the
filesystem is dirty.
Note: If using lilo, then add read-only to your linux setup in your lilo config file (Usually /etc/lilo.conf)
If you often get device busy errors on shutdown that leave the filesystem in
need of an fsck upon reboot, here is a simple fix:
To /etc/rc.d/init.d/halt or /etc/rc.d/rc.0, add the line
mount -o remount,ro /mount.dir
for all your mounted filesystems except /, before the call to umount -a. This
means if, for some reason, shutdown fails to kill all processes and umount the
disks they will still be clean on reboot. Saves a lot of time at reboot for
me.
Simon Amor, simon@foobar.co.uk
ls -l | sort +4n
Or, for those of you really scrunched for space this takes awhile but works
great:
cd /
ls -lR | sort +4n
#!/bin/sh
# /usr/local/bin/print
# a simple formatted printout, to enable someone to
# 3-hole punch the output and put it in a binder
cat $1 | pr -t -o 5 -w 85 | lpr
I call this script 'forall'. Use it like this:
forall /usr/include grep -i ioctl
forall /usr/man grep ioctl
Here's forall:
#!/bin/sh
if [ 1 = `expr 2 \> $#` ]
then
echo Usage: $0 dir cmd [optargs]
exit 1
fi
dir=$1
shift
find $dir -type f -print | xargs "$@"
Here is a simple two-liner which recursively descends a
directory hierarchy removing emacs auto-save (#) and backup (~) files, .o
files, and TeX .log files. It also compresses .tex files and
README files. I call it 'squeeze' on my system.
#!/bin/sh
#SQUEEZE removes unnecessary files and compresses .tex and README files
#By Barry tolnas, tolnas@sun1.engr.utk.edu
#
echo squeezing $PWD
find $PWD \( -name \*~ -or -name \*.o -or -name \*.log -or -name \*\#\) -exec
rm -f {} \;
find $PWD \( -name \*.tex -or -name \*README\* -or -name \*readme\* \) -exec gzip -9 {} \;
ps -aux | sort +4n
-OR-
ps -aux | sort +5n
I do a lot of C programming in my spare time, and I've taken the time to
rig vi to be C friendly. Here's my .exrc:
set autoindent
set shiftwidth=4
set backspace=2
set ruler
What does this do? autoindent causes vi to automatically indent each line
following the first one indented, shiftwidth sets the distance of ^T to 4
spaces, backspace sets the backspace mode, and ruler makes it display the line
number. Remember, to go to a specific line number, say 20, use:
vi +20 myfile.c
Most hackers already have ctags on their computers, but don't use it. It can be
very handy for editing specific functions. Suppose you have a function, in one of
many source files in a directory for a program you're writing, and you want to
edit this function for updates. We'll call this function foo(). You don't
where it is in the source file, either. This is where ctags comes in handy.
When run, ctags produces a file named tags in the current dir, which is a listing of
all the functions, which files they're in and where they are in said files. The
tags file looks like this:
ActiveIconManager iconmgr.c /^void ActiveIconManager(active)$/
AddDefaultBindings add_window.c /^AddDefaultBindings ()$/
AddEndResize resize.c /^AddEndResize(tmp_win)$/
AddFuncButton menus.c /^Bool AddFuncButton (num, cont, mods, func, menu, item)$/
AddFuncKey menus.c /^Bool AddFuncKey (name, cont, mods, func, menu, win_name, action)$/
AddIconManager iconmgr.c /^WList *AddIconManager(tmp_win)$/
AddIconRegion icons.c /^AddIconRegion(geom, grav1, grav2, stepx, stepy)$/
AddStartResize resize.c /^AddStartResize(tmp_win, x, y, w, h)$/
AddToClientsList workmgr.c /^void AddToClientsList (workspace, client)$/
AddToList list.c /^AddToList(list_head, name, ptr)$/
To edit, say AddEndResize() in vim, run:
vim -t AddEndResize
This will bring the appropriate file up in the editor, with the cursor located at the beginning
of the function.
This is a fairly common problem, almost to the point of being a FAQ. I don't
know if RedHat has fixed this bug in their distribution, but you can repair it
yourself. If you look in your /etc/hosts file, you will find it looks something
like:
127.0.0.1 localhost yourbox
When sendmail starts, it does a lookup on your hostname(in this example, yourbox).
It then finds that the IP for yourbox is 127.0.0.1, sendmail doesn't like this,
so it does the lookup again. It continues with this for a while until it
eventually gives up and exits. Fixing the problem is extremely easy,
edit your /etc/hosts file and change it to something like this:
127.0.0.1 localhost
10.56.142.1 yourbox
RedHat's distribution comes with color-ls, however why they don't configure
it for colour use by default is beyond me. Here's to fix it.
First, type eval `DIRCOLORS`
Next, alias ls='ls --color=auto'
And put the 'alias.....' in your /etc/bashrc
What if you're compiling and you've missed a library that needed linking in?
All gcc reports are function names... Here's a simple command that'll
find what you're looking for:
for i in *; do echo $i:;nm $i|grep tgetnum 2>/dev/null;done
Where tgetnum is the name of the function you're looking for.
You probably compiled the program into a binary named test, didn't you?
Linux has a program called test, which tests if a certain condition is true,
it never produces any output on the screen. Instead of just typing
test, try: ./test
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