Bash Shell為UNIX的殼層程式，不但是GNU作業系統的殼層程式，也是Linux及Mac OS X的預設殼層程式，算是各種Linux版本上最常見的公用程式。它採用命令列介面，允許使用者輸入文字命令，也可讓使用者遠端下達指令（如透過ssh或telnet）。
Bash是一個指令列shell （殼層）程式，廣泛存在於 Linux、BSD 和 Mac OS X 等UNIX-based的作業系統，使用者只要將指令輸入到一個簡單的文字式視窗，作業系統便會依指令運作。

reset="\033[0m"
red="\033[31m"
green="\033[32m"
yellow="\033[33m"
cyan="\033[36m"
white="\033[37m"

printf "$cyan helloworld $reset\n"
printf "$red foobar $reset\n"

myarray=(
  red
  green
  yellow
  cyan
  white
)

echo ${myarray[0]}
echo ${myarray[1]}
echo ${myarray[@]}

echo ${0}
echo ${1}
echo ${1:-foo}

#!/bin/bash
curl -s http://ip.taobao.com//service/getIpInfo.php?ip=${1:-myip} | jq

shell> foo='() { echo not patched; }' bash -c foo

shell> env x='() { :;}; echo vulnerable' bash -c "echo this is a test"

# for name [ [ in [ word ... ] ] ; ] do list ; done

for seq in 1 2 3 4 5 6 7 8 9 10; do
  echo $seq
done

for seq in 1 2 3 4 5 6 7 8 9 10; do
  printf "%03d\n" $seq
done

for seq in $(seq 1 2 20); do
  echo $seq
done

# for (( expr1 ; expr2 ; expr3 )) ; do list ; done
for (( i=1; i<=5; i++ )); do
  echo $seq
done

# 無限迴圈
for (( ; ; )); do
  echo "Hello World!"
done

((expression))
expression1 && expression2
[[ expression ]]

-eq
-ne
-lt
-le
-gt
-ge

#!/bin/bash
while true
do
  echo "$(date +"%Y-%m-%d %T") $(netstat -ntap | grep 46998 | grep ESTABLISHED | wc -l)" | tee -a LogFile
  sleep 2
done

#!/bin/bash

i=1
while [ $i -le 5 ]
do
  echo $i
  (( i++ ))
done

while read line ; do
  # echo $line
  printf "%2d\n" $line
  printf "%.2f\n" $line  
done < <(cat /samples/comics.lst)

IFS=':'
while read name junk junk1 junk2 junk3
do
  echo $name
done </samples/comics.lst

參考網站：

RAM_SIZE=$(free -b | grep Mem | awk '{print $2}')
HOSTNAME=`/bin/hostname -f`

uname -m | grep 64
IS_64BIT=$?
#BIT_WIDTH=64
BIT_WIDTH=32
CONNTRACK_MAX=$(($RAM_SIZE / 16384 * 32 / $BIT_WIDTH))

echo $IS_64BIT
echo $CONNTRACK_MAX
echo $RAM_SIZE
echo $RANDOM

echo My home directory is $HOME
echo "My current directory is $PWD"

#!/bin/bash

ip=$(curl -s https://api.ipify.org)
echo "My public IP address is: $ip"

參考網站：

ipify

#!/bin/bash
if COMMANDS; then COMMANDS;
else COMMANDS;
fi

# You may uncomment the following lines if you want `ls' to be colorized:
export LS_OPTIONS='--color=auto'
eval "`dircolors`"
alias ls='ls $LS_OPTIONS'
alias ll='ls $LS_OPTIONS -l'
alias l='ls $LS_OPTIONS -lA'

# Some more alias to avoid making mistakes:
# alias rm='rm -i'
# alias cp='cp -i'
# alias mv='mv -i'

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

daemon - turns other processes into daemons

安裝

shell> sudo apt-get install daemon
shell> daemon -r ./test.sh

test.sh

#!/bin/bash

# 無限迴圈
while true; do
  echo "$(date +"%Y-%m-%d %T") > /dev/shm/date.txt 
  sleep 2
done

shell> start-stop-daemon --start --background --exec /root/test.sh
shell> start-stop-daemon --stop --name test.sh

參考網站：

-n do not output the trailing newline

-e enable interpretation of backslash escapes

\r carriage return

Carriage Return 歸位字元 ↵

#!/bin/bash

echo -ne '#####                     (33%)\r'
sleep 1
echo -ne '#############             (66%)\r'
sleep 1
echo -ne '#######################   (100%)\r'
echo -ne '\n'

export HISTCONTROL='ignoredups'

shell> dpkg --print-architecture

bash

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安裝

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