sed  '/mypattern/d' file

Deletes all lines that contain the regular expression “mypattern”.

In-place replacement:

sed --in-place '/mypattern/d' file1

sed also supports making backups with e.g. –in-place=.backup .

while ! cat /proc/loadavg |cut -f2 -d ' '|grep '0\.00'; do sleep 10m; done && poweroff

Alternatively:

while ps 12345; do sleep 10m; done && poweroff

for i in 1 2 3 4; do grep -v $i; done

So I wrote this chaining tool that does the job in the obvious way:

chain.sh

#!/bin/bash
commands_file=$1
a=$(mktemp)
b=$(mktemp)
cat > $a
while read line; do
$line < $a > $b
mv $b $a
done < $commands_file
cat $a
rm $a

With this, you can do:

for i in 1 2 3 4; do
echo grep -v $i >> mycommands.txt
done
script/chain.sh mycommands.txt

lang=”bash”

## Makefile for foo

## help: this clutter

help:

        @grep -E '^## ' Makefile|grep -v ':'|sed 's,^## ,,g'

        @echo This Makefile has the targets:

        @grep -E '^## [.a-z]{2,}:' Makefile|sed 's,^## *,\t,g' |sed 's,: ,\t,g'

## tests: run the tests

tests: tests.exe

        ./tests.exe ${TESTNR}

Output of

$ make help

Makefile for foo

This Makefile has the targets:

	help	this clutter

	all	

	tests	run the tests

...

Nice, leet and meta. :-)

Some more words on Makefiles: You can use something like

CFLAGS=-O3 -Wall -Werror -Wextra -g -ansi -pedantic ${CCFLAGS}

and pass CCFLAGS from outside. This avoids having many many versions while trying to test things out. For example:

$ CCFLAGS="-DDEBUG -Os -DUSED_ALGORITHM=binsearch2" make tests

(if you didn’t notice yet, -DFOO lets you jump inside #ifdef FOO).

Steps:

1. create ssh-key on new collaborators computer (ssh-keygen)
2. create github user
3. add public-key to github user account
4. let the project owner add you as project member
5. git clone git@…

Where 1 < 3, 1 < 2 < 4, 2 < 5 if that means anything to you ;-)

* it works with git remote

So, what I did was wrap maven in a script that colorizes the output. The result looks like this:

This is how to do it:
create the file ~/bin/mvn with the following content (mvn (0 KB))

#!/bin/bash
/usr/bin/mvn $* | sed -e 's/Tests run: \([^,]*\), Failures: \([^,]*\), Errors: \([^,]*\), Skipped: \([^,]*\)/Tests run: \1, Failures: \2, Errors: \3, Skipped: \4/g' \
-e 's/\(\[WARN\].*\)/\1/g' \
-e 's/\(\[INFO\].*\)/\1/g' \
-e 's/\(\[ERROR\].*\)/\1/g'

replace /usr/bin/mvn with wherever your mvn is (find out with which mvn).
Double-check that you get the encoding right, the weird sign should be hexadecimal 1b. Use a editor that supports encodings for copy+paste.
Give your ~/bin/mvn execute permissions (chmod +x ~/bin/mvn)

Try it out: call ~/bin/mvn in one of your maven projects

What is left to do is to register your new mvn-wrapper so it is called everytime.
Add the following line to your ~/.bashrc :

alias mvn=~/bin/mvn

Execute the command you just added in your running shells so you can use it there too.

You are done.

Changing the distributed mvn startup script

Even better, but a little more intrusive (you need root rights):
change the distributed mvn file. It is a bash script actually.
In gentoo:

 $ which mvn
/usr/bin/mvn
$ file /usr/bin/mvn
/usr/bin/mvn: symbolic link to `/usr/share/maven-bin-2.0/bin/mvn'
$ file /usr/share/maven-bin-2.0/bin/mvn
/usr/share/maven-bin-2.0/bin/mvn: Bourne shell script text executable
$ 

Change the last call in that file to:

exec "$JAVACMD" \
$MAVEN_OPTS \
-classpath "${M2_HOME}"/boot/classworlds-*.jar \
"-Dclassworlds.conf=${M2_HOME}/bin/m2.conf" \
"-Dmaven.home=${M2_HOME}"  \
${CLASSWORLDS_LAUNCHER} $QUOTED_ARGS |
sed -e 's/Tests run: \([^,]*\), Failures: \([^,]*\), Errors: \([^,]*\), Skipped: \([^,]*\)/Tests run: \1, Failures: \2, Errors: \3, Skipped: \4/g' \
-e 's/\(\[WARN\].*\)/\1/g' \
-e 's/\(\[INFO\].*\)/\1/g' \
-e 's/\(\[ERROR\].*\)/\1/g'

That way you have it there directly. Maybe the gentoo devs could add a color use-flag. That’d be fun…

timeoutwrapper.sh

#!/bin/bash
# License: BSD License
# author: Ram
# author: Johannes Buchner
TIMEOUT=$1
shift
COMMAND="$*"
if [[ "$TIMEOUT" == "" ]] || [[ "$COMMAND" == "" ]]; then
echo "USAGE: $0 <seconds to wait> <command with arguments>"
exit
fi
$COMMAND &
PRODPID=$!
export PRODPID
# record own PID
export PID=$$
# define exit function
exit_timeout() {
echo "Timeout. Checking for unfinished."
for i in ${PRODPID} ; do
ps -p $i |grep -v "PID TTY"
if [ $? == 0 ] ; then
# process still alive
echo "Sending SIGTERM to process $i"
kill $i
fi
done
# timeout exit
exit
}
# Handler for signal USR1 for the timer
trap exit_timeout SIGUSR1
# starting timer in subshell. It sends a SIGUSR1 to the father if it timeouts.
export TIMEOUT
(sleep $TIMEOUT ; kill -SIGUSR1 $PID) &
# record PID of timer
TPID=$!
# wait for all production processes to finish
wait ${PRODPID}
# Normal exit
echo "All processes ended normal"
# kill timer
kill $TPID

Usage examples:

$ bash timeoutwrapper.sh
USAGE: timeoutwrapper.sh <seconds to wait> <command with arguments>
$ bash timeoutwrapper.sh 1 sleep 3
Timeout. Checking for unfinished.
26612 pts/3    00:00:00 sleep
Sending SIGTERM to process 26612
$ bash timeoutwrapper.sh 4 sleep 3
All processes ended normal
$ bash timeoutwrapper.sh 2 du -sh .
Timeout. Checking for unfinished.
26622 pts/3    00:00:00 du
Sending SIGTERM to process 26622
$

PS: I found the script here and adopted it
http://redflo.de/tiki-index.php?page=Bash+script+with+timeout+function

Anyway, consider you have a ssh server in the internet, and two computers behind different firewalls that only let traffic out. But you want to connect from computer A to computer B.
So you could connect to the ssh server from both computers, but you would need some software that reverses your TCP flow. One of the channels has to be the client and one the server. That might even be possible just using pipes and ssh -L.

Ok, so I thought I was clever until I found the -R option.
What it does is to connects to the ssh server and offers a local service (port) remotely. (-L offers a remote service (port) locally.)
Consequent. And works nicely too!

#!/bin/bash
echo ${BASH_ARGV[ $(( $RANDOM % $# )) ]}

Example:

$ bash randomchooser.sh 1 2 3 4 5 6 7 8 9 120
3