Shell timeout variables (TMOUT) can be very liberal about what is classified as 'activity', like having an editor open. This command string will terminate the login shell for an user with more than a day's idle time.

If you use Linux in a Windows domain and there are N days to expiry, this is how you can change it without resorting to a windows machine.

Remove newlines from output.

One character shorter than awk /./ filename and doesn't use a superfluous cat.

To be fair though, I'm pretty sure fraktil was thinking being able to nuke newlines from any command is much more useful than just from one file.

cat? dd? RTFM

Pipe any output to "grep ." and blank lines will not be printed.

Gets the internal and external IP addresses of all your interfaces, or the ones given as arguments

default stack size is 10M. This makes your multithread app filling rapidly your memory.

on my PC I was able to create only 300thread with default stack size.

Lower the default stack size to the one effectively used by your threads, let you create more.

ex. putting 64k I was able to create more than 10.000threads.

Obviously ...your thread shouldn't need more than 64k ram!!!

Within /proc and /sys there are a lot of subdirectories, which carry pseudofiles with only one value as content. Instead of cat-ing all single files (which takes quite a time) or do a "cat *" (which makes it hard to find the filename/content relation), just grep recursively for . or use "grep . /blabla/*" (star instead of -r flag).

For better readability you might also want to pipe the output to "column -t -s : ".

If you are doing some tests which require reboots (e. g. startup skripts, kernel module parameters, ...), this is very time intensive, if you have got a hardware with a long pre-boot phase due to hardware checks.

At this time, kexec can help, which only restarts the kernel with all related stuff.

First the kernel to be started is loaded, then kexec -e jumps up to start it.

Is as hard as a reboot -f, but several times faster (e. g. 1 Minute instead of 12 on some servers here).

The initial version of this command also outputted extra empty lines, so it went like this:

192.168.166.48

127.0.0.1

This happened on Ubuntu, i haven't tested on anything else.

and, a lot uglier, with sed:

Edit:

Wanted to be shorter than the perl version. Still think that the perl version is the best..

Get the IP address of all your network cards.

Fetches the IPs and ONLY the IPs from ifconfig. Simplest, shortest, cleanest.

Perl is too good to be true...

(P.S.: credit should go to Peteris Krumins at catonmat.net)

Instead of calculating the offset and providing an offset option to mount, let lomount do the job for you by just providing the partition number you would like to loop mount.

gemInst.sh:

#!/bin/bash

for i in $@; do

if [ "$1" != "$i" ]

then

echo /newInstall/gem install $1 -v=\"$i\"

/newInstall/gem install $1 -v="$i"

if [ "$?" != "0" ]

then

echo -e "\n\nGEM INSTALL ERROR: $1\n\n"

echo "$1" > gemInst.err

fi

fi

done

This command displays a clock on your terminal which updates the time every second. Press Ctrl-C to exit.

A couple of variants:

A little bit bigger text:

You can try other figlet fonts, too.

Big sideways characters:

This requires a particular version of banner and a 40-line terminal or you can adjust the width ("30" here).

will show:

installed linux headers, image, or modules: /^ii/!d

avoiding current kernel: /'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d

only application names: s/^[^ ]* [^ ]* \([^ ]*\).*/\1/

avoiding stuff without a version number: /[0-9]/!d

will purge:

only installed apps: /^ii/!d

avoiding current kernel stuff: /'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d

using app names: s/^[^ ]* [^ ]* \([^ ]*\).*/\1/

avoiding stuff without a version number: /[0-9]/!d

Using the grep command, retrieve all lines from any log files in /var/log/ that have one of the problem states

With this command you can get a previous or future date or time. Where can you use this? How about finding all files modified or created in the last 5 mins?

touch -t `echo $(date -d "5 minute ago" "+%G%m%d%H%M.%S")` me && find . -type f -newer me

List all directories created since last week?

touch -t `echo $(date -d "1 week ago" "+%G%m%d%H%M.%S")` me && find . -type d -cnewer me

I'm sure you can think of more ways to use it. Requires coreutils package.

This will issue a shutdown command to the Windows machine. username must be an administrator on the Windows machine. Requires samba-common package installed. Other relevant commands are:

net rpc shutdown -r : reboot the Windows machine

net rpc abortshutdown : abort shutdown of the Windows machine

Type:

net rpc

to show all relevant commands

Really only valuable in a PHP-only project directory. This is using standard linux versions of the tools. On most older BSD variants of sed, use -E instead of -r. Or use: sed 's/\+[[:space:]]\{1,\}//' instead.