從 bash history 查看指令的使用頻率

$ awk '{print $1}' ~/.bash_history | sort | uniq -c | sort -n

References :
Idle Curiosity: Which shell commands loom large?
How do I see what my most used linux command are? - Super User

bash history 忽略特定指令

$ vi ~/.bashrc

export HISTIGNORE="pwd:ls:ls -ltr:unzip *"

References :
15 Examples To Master Linux Command Line History

shell script callback function

myfunc() {
    str=$1

    echo $str
}

callback_handler="myfunc"                                                                                                                  

if [ "$callbak_handler" != "" ]; then
    eval $file_handler asdfghjkl
fi

References :
Friends don't let friends program in shell script | TurnKey GNU/Linux Blog

shell script handle signal

my_signal_handler() {
    echo '....'
}

trap 'my_signal_handler' EXIT HUP TERM INT

References :
Work the Shell - Dealing with Signals | Linux Journal

shell script kill subprocess when exit

jobs=()
trap '((${#jobs[@]} == 0)) || kill ${jobs[*]} ; exit' EXIT HUP TERM INT
subscript1 & jobs+=($!)
subscript2 & jobs+=($!)

References :

zsh - Killing subprocesses after the script has finished or is killed - Unix & Linux Stack Exchange

append value to bash array

ARR=()
ARR+=(1)
ARR+=(2)

References :
Bash: add value to array without specifying a key - Stack Overflow

inotifywait background job pid

jobs=()
(echo "$BASHPID" > pid-file; exec inotifywait -m ...) | while IFS= read -r...
jobs+=(`pid-file`)

 

 

 

 

References :
Obtaining PID of command earlier in Pipeline

pipe out to shell script function

References :
Pipe output to function - Bash | Unix Linux Forums | Shell Programming and Scripting

Bash 快捷鍵 shortcuts

Alt + U 遊標後一個單字都改成英文大寫
Alt + l 遊標後一個單字都改成英文小寫
Alt + C 遊標後一個單字改成英文開頭大寫
Alt + . 插入最後一個 history 中的文字

shell script regular expression

print only match string

$ uptime | grep -o '[0-9]\+ users'

bash script if / else / fi statements

Reference :
Bash scripting Tutorial

bash script read file

FILE='/etc/passwd'
x=0
while [ $x -lt $(cat $FILE | wc -l) ]
do
   let x=x+1
   head -n $x $FILE | tail -n 1
done

$ while read line; do echo -e "$line\n"; done < file.txt

Reference :
bash shell script read file line by line
How to read a file line by line

bash script array

Reference :
瘋狂帽客's Blog: bash下array的幾種使用方法

bash: no job control in this shell

Reference :
pagx - ChinaUnix博客 - IT人与你分享快乐生活