Commands by andreasS

Commands by andreasS (5)

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Sysadmin day date of any given year

Calculate the date of Sysadmin day (last Friday of July) of any given year Show Sample Output
This is sample output - yours may be different.
```
Jul 31
```
1

YEAR=2015; echo Jul $(ncal 7 $YEAR | awk '/^Fr/{print $NF}')

andreasS · 2014-08-17 11:12:09 9
Sysadmin day date of any given year

Calculate Sysadmin day of any given year using 2 `date`. Code based on http://stackoverflow.com/a/5656859/196133 Show Sample Output
This is sample output - yours may be different.
```
Jul 31
```
0

YEAR=2015; date -d${YEAR}0801-$(date -d${YEAR}0801+2days +%u)days +%b\ %e

andreasS · 2014-08-17 11:06:25 10
Sysadmin day date of any given year

Calculate the date of Sysadmin day (last Friday of July) of any given year Show Sample Output
This is sample output - yours may be different.
```
Jul 31
```
0

YEAR=2015; ncal 7 $YEAR | sed -n 's/^Fr.* $[^ ]\+$ *$/Jul \1/p'

andreasS · 2014-08-17 11:04:02 9
Print file content in reverse order

Show Sample Output
This is sample output - yours may be different.
```
$ echo -e "1\n2\n3" | tac
3
2
1
```
-3

tac [FILE]

andreasS · 2013-05-09 09:19:51 8
Print a bar graph

WIDTHL=10 and WIDTHR=60 are setting the widths of the left and the right column/bar. BAR="12345678" etc. is used to create a 80 char long string of "="s. I didn't know any shorter way. If you want to pipe results into it, wrap the whole thing in ( ... ) I know that printing bar graphs can be done rather easily by other means. Here, I was looking for a Bash only variant. Show Sample Output
This is sample output - yours may be different.
```
$ cat dataset.dat
Irene     10
Karen     37
Andreas   41
Beatrice  23
$ SCALE=1; WIDTHL=10; WIDTHR=60; BAR="12345678"; BAR="${BAR//?/==========}"; while read LEFT RIGHT rest ; do RIGHT=$((RIGHT/SCALE)); printf "%${WIDTHL}s: %-${WIDTHR}s\n" "${LEFT:0:$WIDTHL}" "|${BAR:0:$RIGHT}*"; done < dataset.dat
     Irene: |==========*
     Karen: |=====================================*
   Andreas: |=========================================*
  Beatrice: |=======================*
```
0

SCALE=3; WIDTHL=10; WIDTHR=60; BAR="12345678"; BAR="${BAR//?/==========}"; while read LEFT RIGHT rest ; do RIGHT=$((RIGHT/SCALE)); printf "%${WIDTHL}s: %-${WIDTHR}s\n" "${LEFT:0:$WIDTHL}" "|${BAR:0:$RIGHT}*"; done < dataset.dat

andreasS · 2011-08-22 19:35:21 8

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Delete all empty lines from a file with vim

If you need to delete lines that may contain space characters (such as tabs or spaces) as well as empty ones, try: $:v/\S/d Just an alternative.

Browse system RAM in a human readable form

This command lets you see and scroll through all of the strings that are stored in the RAM at any given time. Press space bar to scroll through to see more pages (or use the arrow keys etc). Sometimes if you don't save that file that you were working on or want to get back something you closed it can be found floating around in here! The awk command only shows lines that are longer than 20 characters (to avoid seeing lots of junk that probably isn't "human readable"). If you want to dump the whole thing to a file replace the final '| less' with '> memorydump'. This is great for searching through many times (and with the added bonus that it doesn't overwrite any memory...). Here's a neat example to show up conversations that were had in pidgin (will probably work after it has been closed)... $sudo cat /proc/kcore | strings | grep '([0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\})' (depending on sudo settings it might be best to run $sudo su first to get to a # prompt)

Determine space taken by files of certain type

Just how much space are those zillions of database logs taking up ? How much will you gain on a compression rate of say 80% ? This little line gives you a good start for your calculations.

Search and play youtube videos directly to terminal (no X needed)

pyt 'Stairway to heaven - Led Zeppelin' pyt 'brain damage - Pink Floyd' No web browser or even X needed. Just a cli and internet connection! mplayer is pauseable and can skip ahead This may break if youtube changes their search html.

list block devices

Shows all block devices in a tree with descruptions of what they are.

Create an SSH SOCKS proxy server on localhost:8000 that will re-start itself if something breaks the connection temporarily

This command will log you into somehost via SSH and then go into the background (-f). From there, you can point e.g. firefox at localhost:8000 as a SOCKS proxy. Autossh will use port 20000 and 20001 to send and receive test data on those ports to ensure the SSH tunnel is still running, and will try to re-start the tunnel if it goes down. Make sure you have ssh-agent running, or passwordless ssh keys distributed between the two hosts.

Get AWS temporary credentials ready to export based on a MFA virtual appliance

You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

move you up one directory quickly

In bash, this turns on auto cd. If a command is just a directory name, it cd's into that directory.

Copy modification timestamp from one file to another.

list block devices

Shows all block devices in a tree with descruptions of what they are.

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