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Insert a line at the top of a text file without sed or awk or bash loops

Just use '-' to use STDIN as an additional input to 'cat'
This is sample output - yours may be different.
1

echo "New first line" | cat - file.txt > newfile.txt; mv newfile.txt file.txt

gpenguin · 2018-10-18 18:54:24 0
Insert a line at the top of a text file without sed or awk or bash loops

Yet another way to add a line at the top a of text file with the help of the tac command (reverse cat).
This is sample output - yours may be different.
0

tac myfile.txt > /tmp/temp; echo "my line" >> /tmp/temp; tac /tmp/temp > myfile.txt

thargos · 2018-10-17 16:16:49 1
Get all documents (doc,docx,xls,xlsx,pdf,ppt,pptx,...) linked in a webpage
This is sample output - yours may be different.
3

curl https://www.domain.com/ | grep -Eo "(http|https)://[a-zA-Z0-9./?=_-]*.*(doc|docx|xls|xlsx|ppt|pptx|pdf)" | sort | uniq > list.txt | wget list.txt

Repie · 2018-10-16 08:54:45 0
Dump man page as clean text

Dumping man pages to text typically retains certain formatting such as foo^H^H^H___ for underscoring, and reverse-line feeds (not sure why). 'col -bx' removes these. Show Sample Output
This is sample output - yours may be different.
```
$ man2txt 1 cat | head    
CAT(1)                           User Commands                          CAT(1)

NAME
       cat - concatenate files and print on the standard output

SYNOPSIS
       cat [OPTION]... [FILE]...

DESCRIPTION
       Concatenate FILE(s) to standard output.
```
0

man2txt() { man "$@" | col -bx ;}

bartonski · 2018-10-14 01:38:04 0
Get a diff of two json arrays

jq is amazing for manipulating json on the commandline, but the developers have some weird ideas about how to handle shell redirections. This command works around them. Further reading: https://github.com/stedolan/jq/issues/1110
This is sample output - yours may be different.
2

diff <(jq . -M -S < old.json) <(jq . -M -S < new.json)

malathion · 2018-10-11 20:59:48 0
Create and access directory at the same time

The previous alternative dont work (the cd command was missing).
This is sample output - yours may be different.
3

mkdir [[folder]] && cd $_

mlinoba · 2018-10-11 16:40:53 1
Continuous random string of text
This is sample output - yours may be different.
0

while true; do sleep .15; head /dev/urandom | tr -dc A-Za-z0-9; done

allyman17 · 2018-10-10 18:57:34 1
Disable updates for installed Chrome plugins

This will allow you to ensure you don't get nagged by updates and also protects you from watering hole attacks! Please be sure to make sure your plugins don't have any security issues! Backups are manifext.jason.bak credit @Jay https://chat.counterpoint.info
This is sample output - yours may be different.
0

find / -iname "manifest.json" -exec sed 's/\"update_url\": \"http/\"update_url\": \"hxxp/g' -i.bak '{}' \;

operat0r · 2018-10-09 19:50:31 0
Create and access directory at the same time

Create and access directory (edited)
This is sample output - yours may be different.
0

mkdir [folder-name] && cd $_

ehmuidifici · 2018-10-09 18:48:16 3
Toggle the Touchpad on or off
This is sample output - yours may be different.
0

tp=$(synclient -l | grep TouchpadOff | awk '{ print $3 }') && tp=$((tp==0)) && synclient TouchpadOff=$tp

jny · 2018-10-09 07:42:32 0
get all Google ipv4 subnets for a iptables firewall for example

a bit shorter, parenthesis not needed but added for clarity Show Sample Output
This is sample output - yours may be different.
```
35.190.247.0/24
64.233.160.0/19
66.102.0.0/20
66.249.80.0/20
72.14.192.0/18
74.125.0.0/16
108.177.8.0/21
173.194.0.0/16
209.85.128.0/17
216.58.192.0/19
216.239.32.0/19
```
1

nslookup -q=TXT _netblocks.google.com | grep -Eo 'ip4:([0-9\.\/]+)' | cut -d: -f2

jseppe · 2018-10-05 18:19:15 2
Create a role on the Chef server with a description
This is sample output - yours may be different.
0

knife role create role-name --description "this is a role that does cool stuff"

niko47 · 2018-10-05 16:00:41 0
get all Amazon cloud (amazonws etc) ipv6 subnets
This is sample output - yours may be different.
1

curl -s https://ip-ranges.amazonaws.com/ip-ranges.json | awk -F'"' '/ipv6_prefix/ {print $4}'

emphazer · 2018-10-05 13:01:03 0
get all Amazon cloud (amazonws etc) ipv4 subnets
This is sample output - yours may be different.
1

curl -s https://ip-ranges.amazonaws.com/ip-ranges.json | awk -F'"' '/ip_prefix/ {print $4}'

emphazer · 2018-10-05 12:59:33 0
get all Google ipv4 subnets for a iptables firewall for example
This is sample output - yours may be different.
2

nslookup -q=TXT _netblocks.google.com | grep -Po '\b([0-1]?\d{1,2}|2[0-4]\d|25[0-5])(\.([0-1]?\d{1,2}|2[0-4]\d|25[0-5])){3}(/\d{1,2})\b'

emphazer · 2018-10-05 12:50:48 0
Use jq to validate and pretty-print json output

The `jq` tool can also be used do validate json files and pretty print output: ` jq < file.json` Available on several platforms, including newer debian-based systems via `#sudo apt install jq`, mac via `brew install jq`, and from source https://stedolan.github.io/jq/download/ This alternative to the original avoids the useless use of cat Show Sample Output
This is sample output - yours may be different.
```
success:
{
  "foo": "bar"
}

error:
$ jq < file.json
parse error: Unmatched '}' at line 1, column 15
```
0

jq < file.json

malathion · 2018-10-03 18:46:46 0
Convert hex data to binary with a bash function (requires bash v4+ for the @^^ lowercase hex demangling)

Use this function with bash version 4+ to convert arbitrary hexadecimal sequences to binary. If you don't have bash 4+ then modify the lowercase to uppercase demangling statement s=${@^^} to set s equal to the uppercase hex input or the bc command throws an input parser error. Show Sample Output
This is sample output - yours may be different.
```
$ bash --version
GNU bash, version 4.4.23(1)-release (x86_64-apple-darwin17.5.0)
$ hex2bin 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
0000000000000000000000000000000000000000000110011101011001101000100111000000100001011010111000010110010110000011000111101001001101001111111101110110001110101110010001101010001010100110110000010111001010110011111100011011011000001010100011001110001001101111
```
0

hex2bin () { s=${@^^}; for i in $(seq 0 1 $((${#s}-1))); do printf "%04s" `printf "ibase=16; obase=2; ${s:$i:1};\n" | bc` ; done; printf "\n"; }

RiskNerd · 2018-10-02 22:02:33 0
use jq to validate and pretty-print json output

the `jq` tool can also be used do validate json files and pretty print output `cat file.json | jq` available on several platforms, including newer debian-based systems via `#sudo apt install jq`, mac via `brew install jq`, and from source https://stedolan.github.io/jq/download/ Show Sample Output
This is sample output - yours may be different.
```
success:
{
  "foo": "bar"
}

error:
$ echo '{"foo":{"bar":}}'| jq
parse error: Unmatched '}' at line 1, column 15
```
2

cat file.json | jq

daemeon · 2018-10-01 23:05:27 0
Close specify detached screen

-X Send the specified command to a running screen session. -S Option to specify the screen session if you have several screen sessions running. screen -ls for listing current screens and its sessionname
This is sample output - yours may be different.
1

screen -X -S [sessionname] quit

FanMix · 2018-10-01 14:30:01 0
Kill any lingering ssh processes

Also ignoring "sshd" server is necessary since you should not kill ssh server processes.
This is sample output - yours may be different.
1

ps aux | grep ssh | grep -v grep | grep -v sshd | awk {'print $2'} | xargs -r kill -9

user2390 · 2018-10-01 04:49:09 2

create ICO file with more than one image

requires imagemagick. -background transparent is of course optional. Show Sample Output

convert -background transparent input.png -define icon:auto-resize=16,32,48,64,128 favicon.ico

emphazer · 2018-09-27 13:12:03 0

loop files with SPACES on their names

use '*' instead of 'ls'
This is sample output - yours may be different.
-1

for f in *;do echo $f;done

famaral · 2018-09-21 14:27:23 2

Nginx - print all optional modules before compilation

wget http://nginx.org/download/nginx-1.15.3.tar.gz && tar -xzf 1.15.3.tar.gz && cd nginx-1.15.3 Show Sample Output

This is sample output - yours may be different.

  --with-threads                     # thread pool support
  --with-file-aio                    # file AIO support
  --with-http_ssl_module             # ngx_http_ssl_module
  --with-http_v2_module              # ngx_http_v2_module
  --with-http_realip_module          # ngx_http_realip_module
  --with-http_addition_module        # ngx_http_addition_module
  --with-http_xslt_module            # ngx_http_xslt_module
  --with-http_image_filter_module    # ngx_http_image_filter_module
  --with-http_geoip_module           # ngx_http_geoip_module
  --with-http_sub_module             # ngx_http_sub_module
  --with-http_dav_module             # ngx_http_dav_module
  --with-http_flv_module             # ngx_http_flv_module
  --with-http_mp4_module             # ngx_http_mp4_module
  --with-http_gunzip_module          # ngx_http_gunzip_module
  --with-http_gzip_static_module     # ngx_http_gzip_static_module
  --with-http_auth_request_module    # ngx_http_auth_request_module
  --with-http_random_index_module    # ngx_http_random_index_module
  --with-http_secure_link_module     # ngx_http_secure_link_module
  --with-http_degradation_module     # ngx_http_degradation_module
  --with-http_slice_module           # ngx_http_slice_module
  --with-http_stub_status_module     # ngx_http_stub_status_module
  --with-http_perl_module            # ngx_http_perl_module
  --with-mail                        # POP3/IMAP4/SMTP proxy module
  --with-mail_ssl_module             # ngx_mail_ssl_module
  --with-stream                      # TCP/UDP proxy module
  --with-stream_ssl_module           # ngx_stream_ssl_module
  --with-stream_realip_module        # ngx_stream_realip_module
  --with-stream_geoip_module         # ngx_stream_geoip_module
  --with-stream_ssl_preread_module   # ngx_stream_ssl_preread_module
  --with-google_perftools_module     # ngx_google_perftools_module
  --with-cpp_test_module             # ngx_cpp_test_module
  --with-pcre-jit                    # PCRE with JIT compilation support


# if you want to see all removable modules just do
./configure --help | grep -P "^ +--without[^=]+(_module( |$)| (module|support)$)" | sed -r 's/((dis|en)able|build) /# /'

  --without-select_module            # select module
  --without-poll_module              # poll module
  --without-http_charset_module      # ngx_http_charset_module
  --without-http_gzip_module         # ngx_http_gzip_module
  --without-http_ssi_module          # ngx_http_ssi_module
  --without-http_userid_module       # ngx_http_userid_module
  --without-http_access_module       # ngx_http_access_module
  --without-http_auth_basic_module   # ngx_http_auth_basic_module
  --without-http_mirror_module       # ngx_http_mirror_module
  --without-http_autoindex_module    # ngx_http_autoindex_module
  --without-http_geo_module          # ngx_http_geo_module
  --without-http_map_module          # ngx_http_map_module
  --without-http_split_clients_module # ngx_http_split_clients_module
  --without-http_referer_module      # ngx_http_referer_module
  --without-http_rewrite_module      # ngx_http_rewrite_module
  --without-http_proxy_module        # ngx_http_proxy_module
  --without-http_fastcgi_module      # ngx_http_fastcgi_module
  --without-http_uwsgi_module        # ngx_http_uwsgi_module
  --without-http_scgi_module         # ngx_http_scgi_module
  --without-http_grpc_module         # ngx_http_grpc_module
  --without-http_memcached_module    # ngx_http_memcached_module
  --without-http_limit_conn_module   # ngx_http_limit_conn_module
  --without-http_limit_req_module    # ngx_http_limit_req_module
  --without-http_empty_gif_module    # ngx_http_empty_gif_module
  --without-http_browser_module      # ngx_http_browser_module
  --without-http_upstream_hash_module
  --without-http_upstream_ip_hash_module
  --without-http_upstream_least_conn_module
  --without-http_upstream_random_module
  --without-http_upstream_keepalive_module
  --without-http_upstream_zone_module
  --without-mail_pop3_module         # ngx_mail_pop3_module
  --without-mail_imap_module         # ngx_mail_imap_module
  --without-mail_smtp_module         # ngx_mail_smtp_module
  --without-stream_limit_conn_module # ngx_stream_limit_conn_module
  --without-stream_access_module     # ngx_stream_access_module
  --without-stream_geo_module        # ngx_stream_geo_module
  --without-stream_map_module        # ngx_stream_map_module
  --without-stream_split_clients_module
  --without-stream_return_module     # ngx_stream_return_module
  --without-stream_upstream_hash_module
  --without-stream_upstream_least_conn_module
  --without-stream_upstream_random_module
  --without-stream_upstream_zone_module

inspiration source:
https://gist.github.com/magnetikonline/6b66bbb3aade707d0a23

# notice: 
# i removed select and poll method because most kernels use kqueue
# and it will be built automaticly if kqueue is not supported

emphazer · 2018-09-14 12:54:06 0

urlencoding with one pure BASH builtin

opposite of https://www.commandlinefu.com/commands/view/10014/urldecoding-with-one-pure-bash-builtin ;-) Show Sample Output
This is sample output - yours may be different.
```
URLEncode https://www.commandlinefu.com/commands/by/emphazer

https%3A%2F%2Fwww.commandlinefu.com%2Fcommands%2Fby%2Femphazer
```
0

function URLEncode { local dataLength="${#1}"; local index; for ((index = 0;index < dataLength;index++)); do local char="${1:index:1}"; case $char in [a-zA-Z0-9.~_-]) printf "$char"; ;; *) printf "%%%02X" "'$char"; ;; esac; done; }

emphazer · 2018-09-14 12:08:10 0
Unlock VMs in Proxmox

Unlock your VMS to avoid problems after some failed tasks ended. Show Sample Output
This is sample output - yours may be different.
```
...
Unlocking: 10098
Unlocked
Unlocking: 10120
Unlocked
Unlocking: 11018
Unlocked
Unlocking: 20003
Unlocked
Unlocking: 20023
...
```
0

for i in $(qm list | awk '{ print $1 }' | grep -v VMID); do echo "Unlocking:" $i; qm unlock $i; echo "Unlocked"; done

arkalira · 2018-09-13 08:35:12 0
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Converts all windows .URL shortcuts in a directory to linux (gnome) .desktop shortcuts

print file without duplicated lines using awk

This create an array 'a' with wole lines. only one occurrence of each line - Not Get lines ++ !

Create Encrypted WordPress MySQL Backup without any DB details, just the wp-config.php

The coolest way I've found to backup a wordpress mysql database using encryption, and using local variables created directly from the wp-config.php file so that you don't have to type them- which would allow someone sniffing your terminal or viewing your shell history to see your info. I use a variation of this for my servers that have hundreds of wordpress installs and databases by using a find command for the wp-config.php file and passing that through xargs to my function.

Use a decoy while scanning ports to avoid getting caught by the sys admin :9

Scan for open ports on the target device/computer (192.168.0.10) while setting up a decoy address (192.168.0.2). This will show the decoy ip address instead of your ip in targets security logs. Decoy address needs to be alive. Check the targets security log at /var/log/secure to make sure it worked.

Generate Random Text based on Length

Random text of length "$1" without the useless cat command.

List all symbolic links in a directory matching a string

Finds all symbolic links in the specified directory which match the specified string pattern. I used this when upgrading from an Apple-supported version of Java 6 (1.6.0_65) to an Oracle-supported version (1.7.0_55) on Mac OS X 10.8.5 to find out which executables were pointing to /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands (Apple version) vs. /Library/Java/JavaVirtualMachines/jdk1.7.0_55.jdk/Contents/Home/bin (Oracle version). However, it appears the current JDK installation script already takes care of modifying the links.

Which processes are listening on a specific port (e.g. port 80)

swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Rename files in batch

Remove all unused kernels with apt-get

Note the double space: "...^ii␣␣linux-image-2..." Like 5813, but fixes two bugs: [1]This leaves the meta-packages 'linux-headers-generic' and 'linux-image-generic' alone so that automatic upgrades work correctly in the future. [2]Kernels newer than the currently running one are left alone (this can happen if you didn't reboot after installing a new kernel). I'm bummed that this took 228 characters. I'd like to see a simpler version.

Transfer large files/directories with no overhead over the network

This invokes tar on the remote machine and pipes the resulting tarfile over the network using ssh and is saved on the local machine. This is useful for making a one-off backup of a directory tree with zero storage overhead on the source. Variations on this include using compression on the source by using 'tar cfvp' or compression at the destination via $ ssh user@host "cd dir; tar cfp - *" | gzip - > file.tar.gz

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