Linux CLI snippets

Loop_dir="path_to_dir"
for entry in "$Loop_dir"/*
do
  echo "$entry"
done

ps -aef —forest

find ./ -type f -print | xargs grep 'foo'

alias afind="find -type f -print | xargs grep"

for file in foo*
do 
  mv "$file" "${file#foo}"
done

for file in foo*; do mv "$file" "${file#foo}"; done;

du -h ./to/the/dir

du -h --max-depth=1 ./

IFS=","
for v in "$@"
do
  echo $v
done

dig -x {{ IP }}

dig +additional {{ your_domain }}

while read line; do
  echo "$line"
done < file.txt

#! /bin/bash
end=$((SECONDS+3))

while [ $SECONDS -lt $end ]; do
    # Do what you want.
    :
done

find . -type f -printf '%T@ %p\n' | sort -n | tail -1 | cut -f2- -d" "

sudo su --preserve-env
# or
sudo su --preserve-environment
# or
sudo -E su -p

curl ifconfig.me
curl ident.me

paste file1 file2

sed -i 's/before/after/g' file.txt

## Sepreated one
#sed -i 1,2d test.txt
#sed -i '/NaN/d' test.txt 
#sed -i 's/: /,/g' test.txt

sed -i '1,2d;/nan/d;s/: /,/g' test.txt

$ date +"%Y-%m-%d"
2021-03-11

$ figlet -c "This is my page"
      _____ _     _       _
     |_   _| |__ (_)___  (_)___   _ __ ___  _   _   _ __   __ _  __ _  ___
       | | | '_ \| / __| | / __| | '_ ` _ \| | | | | '_ \ / _` |/ _` |/ _ \
       | | | | | | \__ \ | \__ \ | | | | | | |_| | | |_) | (_| | (_| |  __/
       |_| |_| |_|_|___/ |_|___/ |_| |_| |_|\__, | | .__/ \__,_|\__, |\___|
                                            |___/  |_|          |___/

$ cat server-if_bond0-up-d-MAX.txt
1615374900,first-line
1615374901,second-line

file_name="myfile.csv"
IFS=","
while read time comment; do
  echo "$time"
  echo "$comment"
done < $file_name

# check from shell
sudo apt install oathtool
oathtool --totp=sha256 "myhexcode"
// oathtool --totp=sha256 "c7b794........................................................9f"

# for AWS
oathtool -b --totp="SHA1" ABCD.....

tree -I dont-search-me
tree -I "complicated1|complicated2|wildcard-also-works*"

apt install -y fping
fping -g -r 1 192.168.122.0/24

eog image.jpg

curl blabla.com | jq "."

jq "." # . is the root of json element
jq ".[2]" # the second element
jq ".foo" # get the value of the key "foo"
jq '.results[] | {id}': from the list results, only extract the key id

img_tags=$(grep -oP "\<img[^\>]*\>" myfile.html)

png_list=$(grep -oP "(?<=\<img\ src\=\')[\d\w\/\-\_]+\.png" myfile.html)

basename $path_contains_slashes

bar(?=bar)     finds the 1st bar ("bar" which has "bar" after it)
bar(?!bar)     finds the 2nd bar ("bar" which does not have "bar" after it)
(?<=foo)bar    finds the 1st bar ("bar" which has "foo" before it)
(?<!foo)bar    finds the 2nd bar ("bar" which does not have "foo" before it)

[\S\s]

#!/bin/bash

file=$1
shared_dir=/usr/local/shared

if [[ -f "$shared_dir/$file" ]]; then
    echo "there is the file already at $shared_dir/$file."
else
    echo "Downloading the file in to $shared_dir"
    curl "https://localhost/myfile" -o $shared_dir/$file
fi

group=$(expr $(date +%V) % 4)

openssl s_client -connect www.google.com:443 2>/dev/null </dev/null |  sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p'

find /lib/modules/$(uname -r) -type f -name '*.ko'

nautilus ./

SCRIPT_DIR=$(dirname "$0")

export NAMESPACE=${NAMESPACE:-default}

aws s3 rm s3://unused-bucket --recursive

mkdir backup-me
cd backup-me
aws s3 sync s3://please-delete-2 ./

for file in ./*; do ls $file | tr '\n' ' '; echo $file | grep foo; done

#!/bin/zsh

# i=0
for first_dir in ./*/ ; do
    echo "$first_dir"
    for file in ./$first_dir/* ; do
        # operate on $file
    done
    # ((i++))
done

rm ./*/*.bak

#for file in ./*/ ; do
#    echo "$file"
#done

./script > /dev/null 2>&1

./script &>/dev/null