Commands by acavagni

Commands by acavagni (12)

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Print all git repos from a user (only curl and grep)
This is sample output - yours may be different.
2

curl -s https://api.github.com/users/<username>/repos?per_page=1000 | grep -oP '(?<="git_url": ").*(?="\,)'

acavagni · 2019-12-11 20:55:13 321
generate random mac-address using md5sum + sed

Show Sample Output
This is sample output - yours may be different.
```
$ date | md5sum | sed -r 's/(..){3}/\1:/g;s/\s+-$//'
78:3a:dc:2a:9c:df
```
1

date | md5sum | sed -r 's/(..){3}/\1:/g;s/\s+-$//'

acavagni · 2019-07-13 10:39:21 39
draw line separator (using knoppix5 idea)

This is a slightly modified version of the knoppix5 user oneliner (https://www.commandlinefu.com/commands/view/24571/draw-line-separator). Show Sample Output
This is sample output - yours may be different.
```
$ seq -s '*' 40 | tr -dc '[*\n]'
***************************************
```
1

seq -s '*' 40 | tr -dc '[*\n]'

acavagni · 2019-07-01 07:24:47 41
unset all http proxy related environment variables in one go in the current shell

Show Sample Output
This is sample output - yours may be different.
```
$ printenv | grep -i proxy
NO_PROXY=.somedomain.sometld,10.0.0.0/8
http_proxy=http://localhost:3128/
HTTPS_PROXY=http://localhost:3128/
https_proxy=http://localhost:3128/
HTTP_PROXY=http://localhost:3128/
$ eval "unset $(printenv | grep -ioP '(?:https?|no)_proxy' | tr '\n' ' ')"
$ printenv | grep -i proxy
$
```
0

eval "unset $(printenv | grep -ioP '(?:https?|no)_proxy' | tr '\n' ' ')"

acavagni · 2019-06-28 10:40:41 37
automatically generate the ip/hostname entry for the /etc/hosts in the current system

I use it after a clean CentOS 7 minimal server installation to automatically populate the /etc/hosts file. Not sure why the installation does not add this entry by itself. Tested on CentOS 7 with the simplest use case: 1 static ip address and the hostname provided during installation. Show Sample Output
This is sample output - yours may be different.
```
[root@dns-server ~]# echo "$(ip addr show dev $(ip r | grep -oP 'default.*dev \K\S*') | grep -oP '(?<=inet )[^/]*(?=/)') $(hostname -f) $(hostname -s)"
10.0.2.10 dns-server.mydomain.lab dns-server

[root@dns-server ~]# echo "$(ip addr show dev $(ip r | grep -oP 'default.*dev \K\S*') | grep -oP '(?<=inet )[^/]*(?=/)') $(hostname -f) $(hostname -s)" >> /etc/hosts

[root@dns-server ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
10.0.2.10 dns-server.mydomain.lab dns-server
```
0

echo "$(ip addr show dev $(ip r | grep -oP 'default.*dev \K\S*') | grep -oP '(?<=inet )[^/]*(?=/)') $(hostname -f) $(hostname -s)"

acavagni · 2019-06-15 16:40:38 47
get a rough estimate about how much disk space is used by all the currently installed debian packages

The vaule is expressed in megabytes Show Sample Output
This is sample output - yours may be different.
```
$ echo $[ ($(dpkg-query -s $(dpkg --get-selections | grep -oP '^.*(?=\binstall)') | grep -oP '(?<=Installed-Size: )\d+' | tr '\n' '+' | sed 's/+$//')) / 1024 ]
4506
```
1

echo $[ ($(dpkg-query -s $(dpkg --get-selections | grep -oP '^.*(?=\binstall)') | grep -oP '(?<=Installed-Size: )\d+' | tr '\n' '+' | sed 's/+$//')) / 1024 ]

acavagni · 2019-06-02 16:35:34 56

get the full description of a randomly selected package from the list of installed packages on a debian system

I put this command on my ~/.bashrc in order to learn something new about installed packages on my Debian/Ubuntu system each time I open a new terminal Show Sample Output

dpkg-query --status $(dpkg --get-selections | awk '{print NR,$1}' | grep -oP "^$( echo $[ ( ${RANDOM} % $(dpkg --get-selections| wc -l) + 1 ) ] ) \K.*")

acavagni · 2019-06-01 13:24:07 62

grep expression (perl regex) to extract all ip addresses from both ip and ifconfig commands output

It uses the following GNU grep options: "-o" which shows only the matching part of the line and "-P" which allows the use of Perl regular expressions. Show Sample Output
This is sample output - yours may be different.
```
[root@docker ~]# ip a | grep -oP '(?<=inet |addr:)(?:\d+\.){3}\d+'
127.0.0.1
10.0.2.15
172.17.0.1

[root@docker ~]# ifconfig  | grep -oP '(?<=inet |addr:)(?:\d+\.){3}\d+'
96.126.108.191
192.168.135.145
127.0.0.1
```
4

ip a | grep -oP '(?<=inet |addr:)(?:\d+\.){3}\d+'

acavagni · 2019-03-21 20:53:06 44

Extract rpm package name, version and release using some fancy sed regex

This command could seem pretty pointless especially when you can get the same result more easily using the rpm builtin queryformat, like: rpm -qa --qf "%{NAME} %{VERSION} %{RELEASE}.%{ARCH}\n" | sort | column -t but nonetheless I've learned that sometimes it can be quite interesting trying to explore alternative ways to accomplish the same task (as Perl folks like to say: There's more than one way to do it!) Show Sample Output

rpm -qa | sed 's/^$.*$-$[^-]\{1,\}$-$[^-]\{1,\}$$/\1 \2 \3/' | sort | column -t

acavagni · 2019-03-14 21:11:45 35

Find the top 10 directories containing the highest number of files

It can be used to pinpoint the path(s) where the largest number of files resides when running out of free i-nodes Show Sample Output

acavagni · 2019-03-06 20:36:14 33

remove comments (even those starting with spaces), empty lines (even those containing spaces) in one grep command

useful for discarding even those comments which start with blanks or those empty lines which contain blanks Show Sample Output
This is sample output - yours may be different.
```
[root@docker ~]# grep -vE '^\s*(#|$)' /etc/nsswitch.conf
passwd:     files sss
shadow:     files sss
group:      files sss
hosts:      files dns myhostname
bootparams: nisplus [NOTFOUND=return] files
ethers:     files
netmasks:   files
networks:   files
protocols:  files
rpc:        files
services:   files sss
netgroup:   nisplus sss
publickey:  nisplus
automount:  files nisplus sss
aliases:    files nisplus
```
6

grep -vE '^\s*(#|$)' textfile

acavagni · 2019-03-05 21:40:02 195

Shows space used by each directory of the root filesystem excluding mountpoints/external filesystems (and sort the output)

Useful to see at glance which directory under the root file is using most space Show Sample Output

find / -maxdepth 1 -type d | xargs -I {} sh -c "mountpoint -q {} || du -sk {}" | sort -n

acavagni · 2019-03-04 11:59:10 46

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See entire packet payload using tcpdump.

Look for English words in /dev/urandom

* to get the English dictionary: wget http://www.mavi1.org/web_security/wordlists/webster-dictionary.txt

Recursive cat - concatenate files (filtered by extension) across multiple subdirectories into one file

Useful if you have to put together multiple files into one and they are scattered across subdirectories. For example: You need to combine all .sql files into one .sql file that would be sent to DBAs as a batch script. You do get a warning if you create a file by the same extension as the ones your searching for. find . -type f -name *.sql -exec cat {} > BatchFile.txt \;

Create a DOS floppy image

mount with: mount -t msdos -o loop ./floppy.img /tmp/mnt

Find files containing string and open in vim

I often use "vim -p" to open in tabs rather than buffers.

cp the file

Copy the file with the given .extension at the source file's location. Eliminates the typing of long paths again and again.

Updating the status on identi.ca using curl.

identica is an open source social networking and micro-blogging service. Based on Laconica, a micro-blogging software package built on the OpenMicroBlogging specification. http://identi.ca/

list block devices

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

Resize an image to at least a specific resolution

This command will resize an image (keeping the aspect ratio) to a specific resolution, meaning the resulting image will never be smaller than this resolution. For example, if we have a 2048x1000 image, the output would be 1229x600, not 1024x600 or 1024x500. Same thing for the height, if the image is 2000x1200, the output would be 1024x614.

Automatically download Ubuntu 10.04 when available

Tested with 9.10 release. Choose whatever torrent client you prefer.

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