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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 0
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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What's this?

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Kill any process with one command using program name

Somtime one wants to kill process not by name of executable, but by a parameter name. In such cases killall is not suitable method.

Inverted cowsay

It's quite fun to invert text using "flip.pl" (ref: http://ubuntuforums.org/showthread.php?t=2078323 ). Slightly more challenging is to flip a whole "cowsay". :-)

Recursively remove all files in a CVS directory

This will search all directories and ignore the CVS ones. Then it will search all files in the resulting directories and act on them.

Clean apt-get and gpg cache and keys

Cleans apt-get and gpg cache and keys

Rename files in batch

small CPU benchmark with PI, bc and time.

$ # 4 cores with 2500 pi digits $ CPUBENCH 4 2500 $. $ every core will use 100% cpu and you can see how fast they calculate it. $ if you do 50000 digitits and more it can take hours or days

Create a mirror of a local folder, on a remote server

Create a exact mirror of the local folder "/root/files", on remote server 'remote_server' using SSH command (listening on port 22) (all files & folders on destination server/folder will be deleted)

Scan a gz file for non-printable characters and display each line number and line that contains them.

Scans the file once to build a list of line numbers that contain non-printable characters Scans the file again, passing those line numbers to sed as two commands to print the line number and the line itself. Also passes the output through a tr to replace the characters with a ?

Ensure that each machine that you log in to has its own history file

On systems where your home directory is shared across different machines, your bash history will be global, rather than being a separate history per machine. This setting in your .bashrc file will ensure that each machine has its own history file.

Send an http HEAD request w/curl

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