Blog.Project13.pl » shell

[terminal heroes] Display git branch in shell prompt (PS1)

Ktoso — Sat, 26 Feb 2011 22:29:01 +0000

I don’t think I’ve blogged about this but I’ve seen this sometime ago and now decided to add it to my .bashrc for good. It’s a simple trick to make an awesome PS1 shell prompt, displaying the branch you are currently on (if you’re in a git versioned directory). Not that I’m forgetting what branch I’m on, but I hope it’ll make me create more branches more often and never “just work on master” :-)

The code comes from http://arnorehn.de/cgi-bin/weblog_basic/index.php?p=34 so big kudos too him :-)

# in your ~/.bashrc for example
alias gitka='gitk –all' #unrelated to this post, but very useful :-)
function formattedGitBranch {
_branch="$(git branch 2>/dev/null | sed -e "/^\s/d" -e "s/^\*\s//")"
test -n "$_branch" && echo -e " @\e[0;32m $_branch"
}
#export PS1="\u@\h \W \[\e[m\]\$(formattedGitBranch) \[\e[1;32m\]\$ \[\e[m\]\[\e[0m\]"
export PS1="\u@\h \W\[\e[m\]\$(formattedGitBranch)\[\e[0m\] \$ "

Cheers and happy hacking!

PS: I’m waiting for my T-shirt and stickers (for training participants) to arrive from github. I’d love they make it in time for SFI but I’m not sure if it’s even possible hmmm…

[Terminal Heroes] sed mastery – group catching

Ktoso — Sat, 09 Oct 2010 19:24:36 +0000

Just a quick sed (the stream editor) example, as someone from work needed it a few minutes ago and I was more happy to supply an quick solution:

# replace the href part

[ktoso@homunculus ~]$ cat sedmastery
<a href="#" id="hibernate">Hibernatea>
<a href="#" id="html">HTMLa>
<a href="#" id="js">JavaScripta>
[ktoso@homunculus ~]$ sed 's|$[^#]*$#$[^>]*$>$[^< ]*$|\1/\3\2>\3|g' sedmastery
<a href="/Hibernate" id="hibernate">Hibernatea>
<a href="/HTML" id="html">HTMLa>
<a href="/JavaScript" id="js">JavaScripta>

Yup, that’s basically it. You may also apply this directly in vim as I’ve showed here a few years ago and you’ll probably need to look some stuff up here or on this awesome sed guide.

Terminal Heroes 8: Memory usage scripts

Ktoso — Wed, 24 Feb 2010 10:54:21 +0000

I have a low-memory VPS running online and thus always have to worry about what uses how much memory… Of course top and my favorite htop are very good tools to check this, but sometimes I just want to get a super simple report if I’m overusing memory or not yet. The bellow scripts (most of them was found online or hacked up from multiple scripts to fit my needs) print simple yet very readable memory usage information.

memused

#!/bin/bash

#if [ $1 = '']; then
# ps auxf | awk '{sum=sum+$6}; END {print sum/1024}';
#else
# ps auxf | grep $1 | awk '{sum=sum+$6}; END {print sum/1024}';
#fi
bean=`cat /proc/user_beancounters` guar=`echo "$bean" | grep vmguar | awk '{ print $4;}'` burst=`echo "$bean" | grep privvm | awk '{ print $5;}'` priv=`echo "$bean" | grep privvm | awk '{ print $2;}'`
let total=guar/256 let used=priv/256 let burst=burst/256
echo "VPS memory usage:"
echo "Used: $used MB"
echo "Total: $total MB"
echo "Burstable to: $burst MB"

Sample output:
VPS memory usage: Used: 296 MB Total: 256 MB Burstable to: 512 MB

memfree

#!/bin/bash

#
# Revised 02-Feb-2007: include kernel memory (kmemsize) in 'used' calculation
# and show percentages in output.
#
BEAN=`cat /proc/user_beancounters`
GUAR=`echo "$BEAN" | grep vmguar | awk '{ print $4;}'`
PRIV=`echo "$BEAN" | grep privvm | awk '{ print $2;}'`
KMEM=`echo "$BEAN" | grep kmem | awk '{ print $3;}'`
let TOTL=$GUAR/256
let KMMB=$KMEM/1048576
let PVMB=$PRIV/256
let USED=$KMMB+$PVMB
let FREE=$TOTL-$USED
if [ "$FREE" -gt "0" ]; then
let UPER=$USED*100/$TOTL
let FPER=100-$UPER
else
let UPER="100"
let FPER="0"
fi
echo "VPS Memory:"
echo " Total: $TOTL mb Used: $USED mb (${UPER}%) Free: $FREE mb (${FPER}%)"

Sample output:
VPS Memory: Total: 256 mb Used: 302 mb (100%) Free: -46 mb (0%)

memheld

#!/bin/bash

grep oomguarpages /proc/user_beancounters | awk '{s=$2;t=$3;u=$4; {print "VPS Memory Usage\nCurrent Held: " s/256 "MB\nMax Held: " t/256 "MB\nBarrier: "u/256"MB" }}'

Sample output:
VPS Memory Usage Current Held: 160.832MB Max Held: 294.605MB Barrier: 256MB

memps

#!/bin/bash

echo "ps axo pmem,pcpu,comm | sort"
ps axo pmem,pcpu,comm | sort

Sample output:
ps axo pmem,pcpu,comm | sort 0.0 0.0 script 0.0 0.0 script 0.1 0.0 init #... 2.2 0.0 httpd 4.0 0.0 mysqld 7.3 0.0 httpd 8.0 0.0 httpd %MEM %CPU COMMAND

memprivmpages

#!/bin/bash

beans=`cat /proc/user_beancounters | grep priv`
max=`echo $beans | awk '{ print $4;}'`
use=`echo $beans | awk '{ print $2;}'`
let "per=$use*100/$max"
let "mb=$use/256"
let "mmb=$max/256"
echo "privvmpages usage: $mb MB ($per% of $mmb)"

Sample output:
privvmpages usage: 296 MB (57% of 512)
For those wondering, yes I do have memory usage above “100%” in the output of some of these scripts, and it’s partially true. A VPS does usually have some guaranteed memory, and some “burstable” – so you can use more than just the guaranteed memory for some period of time. On the mashine I ran this I have 256 guaranteed and a “total” of 512MB – including the burstable memory.

If you like any of these, feel free to use them. I use them by creating a scripts directory and adding it to the PATH, so I can simply invoke them from anywhere.

PS: For more detailed memory usage information (as graphs etc), I’m using Munin and really recommend it. The graphs it draws are really nice, and it doesn’t inflict heavy load on the server, and it can monitor remote hosts if needed!

Kill only Tomcat

Ktoso — Sun, 21 Feb 2010 22:14:47 +0000

There is sometimes the need to kill some JVM, I usually use “killall java” and that works fine as long as that’s in fact what I want – kill ALL. But let’s say i just want to kill Tomcat and not my IDE? The below method works quite well in such an situation:

[ktoso@homunculus ~]$ sudo netstat -lpn | grep 8080

tcp 0 0 :::8080 :::* LISTEN 18525/java
[ktoso@homunculus ~]$ kill 18525 # you might need to add -9 here (SIGKILL)

A quickly hacked up version of an simple shell script to kill this tomcat could look like (I still suck at awk…):

#!/bin/sh

kill -9 `netstat -lpn | grep 8080 | awk '{print $7}' | awk -F/ '{print $1}'`

The above obviously sux, as we’re using two awk commands after another… Ans also in the above examples, I’ve assumed that tomcat is listening on 8080, this may not always be the case, since with mod_proxy_ajp, there is no need fot it to listen on it’s default port and just the one to communicate by AJP. Let’s use it’s name to find it’s PID, we’ll use ps and grep and awk – life is simple with them. :-)
Here’s the final version of this command:

#!/bin/sh

kill -9 `ps aux | grep catalina | awk '{print $2}'`

(Almost) Automatically convert files into PDF

Ktoso — Mon, 16 Nov 2009 00:56:55 +0000

I’m learning Numerical Analysis right now and a friend of mine found some really nice PS files by dr Marian Bubek ( http://www.icsr.agh.edu.pl/~mownit/mownit.html ). I was really happy to see some *.ps but some people from my fellow students started complaining that they’d rather have pdf’s and not ghostscript files (who knows why they’d do..?). Anyways, they all had “manual” repetitious methods for converting the files – even uploading to somewebsite to have them converted over there “in the cloud”… I though of a slightly quicker and more efficient way, here it is, hope you’ll like it. Ah, there is One “non standard” requirement for this to work, you have to install cups-pdf :-)

wget http://www.icsr.agh.edu.pl/~mownit/mownit.html -r –level 1 -A.ps –cut-dirs 4

mv www.icsr.agh.edu.pl/* .
rm -rf www.icsr.agh.edu.pl/
for file in `dir -f *` ; do
lpr -P 'cups-PDF' $file;
echo "press enter when cups is done printing…" #yeah, i got lazy here, one could watch lpq for changes etc.
read oczekiwanie;
mv /home/ktoso/Pulpit/cups-pdf/template.pdf ./$file;
done;
# ________________
#< Happy hacking! >
# —————-
# \ ^__^
# \ (oo)\_______
# (__)\ )\/\
# ||—-w |
# || ||

AWK and multiple lines from shell command

Ktoso — Sun, 15 Nov 2009 15:11:16 +0000

Let’s say you want to read the ps output inside an AWK script, it’s not so simple since system returns an exit code and not the string you want – it’s being sent to stdout, here is a simple trick to read multiple lines from a shell command inside awk:
awk 'BEGIN{while ("ps aux" | getline){ print "test " $1 " test"}}' /dev/null | more

yum: TypeError: rpmdb open failed

Ktoso — Mon, 14 Sep 2009 02:58:24 +0000

I recently had this following fatal error on an CentOS VPS server:
Loaded plugins: fastestmirror error: no dbpath has been set error: cannot open Packages database in /%{_dbpath} Traceback (most recent call last): File "/usr/bin/yum", line 29, in ? yummain.user_main(sys.argv[1:], exit_code=True) File "/usr/share/yum-cli/yummain.py", line 229, in user_main errcode = main(args) File "/usr/share/yum-cli/yummain.py", line 84, in main base.getOptionsConfig(args) File "/usr/share/yum-cli/cli.py", line 184, in getOptionsConfig enabled_plugins=self.optparser._splitArg(opts.enableplugins)) File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 191, in _getConfig self._conf = config.readMainConfig(startupconf) File "/usr/lib/python2.4/site-packages/yum/config.py", line 754, in readMainConfig yumvars['releasever'] = _getsysver(startupconf.installroot, startupconf.distroverpkg) File "/usr/lib/python2.4/site-packages/yum/config.py", line 824, in _getsysver idx = ts.dbMatch('provides', distroverpkg) TypeError: rpmdb open failedBut after some greping the web i found the sollution:#rm /dev/urandom #mknod -m 644 /dev/urandom c 1 9Seems a little like magic, but it fixed the problem. No idea what caused this error though…

Smart webpage migration

Ktoso — Thu, 27 Aug 2009 18:15:15 +0000

I recently had to migrate a big website – about 5GB – to a new server. That could take a while to do, right? Well, maybe if you did it like that (the not smart way):

Oh man, that would take sooo much time...

Thanks goodness I’m not really keen on doing stuff the slow “not_smart” way, and the new server is a dedicated CentOS machine! :-) So, what did I do?

Yeah, no time wasted here!

There’s a lot of ways to accomplish this if you have shell access. You could:

wget -r --user=login --password='pass' ftp://admin:example.com/folder/

ncftp #normal ftp should also work the same way
open ftp://example.com
login
pass
mget -r folder

Yes, SCP is a great tool for this kind of situation, but i couldn’t use it since the old server didn’t have ssh acces :-( Here is how it could be used in such a situation:
```
scp -r login@old.example.com:/home/folder login@new.example.com:/home/folder
```

I used the second method and am quite satisvied with it, as the servers did all the migrating i set up the database and did some other project related stuff… :-)