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Common Usage:
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cd to directory
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touch < file_name > to create file
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open -e < file_name > to edit file , alternative way is vim < file_name >
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.. < file_name > to reload file
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Common Variable:
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$n, such as $1, $2 means Arg1, Arg2 ... and so on.
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$#, aggregate number of params passing thru script or function file.
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$?, means return val or status from above function.
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Script 1
#! /bin/bash # inpath-- path 路徑指向有效的程式，而非僅僅系統預設的程式 in_path() { # once valid return 0, otherwise return 1. cmd=$1 path=$2 result=1 ifs=$IFS IFS=":" for dir in '$path' do if [ -x $dir/$cmd ] ; then result=0 # valid means this program find out the cmd in path fi done IFS=$ifs return $result } check4_cmd_in_path() { var=$1 if [ "$var" != ""] ; then if [ "${var:0:1}" = "/" ] ; then # (a) if [ ! -x $var ] ; then # (b) return 1 fi elif ! in_path $var "PATH" ; then return 2 fi fi } -
Syntax
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(a) 變數切割法
${var:0:1} 解決一個問題有很多方法，例如 $ (echo $var | cut c1)the actual grammar is : ${var:start:size} 變數切分方式 判斷第一字元是否為 / 此為從字串中取得子字串的一種簡寫方法，並且從指定的位移值開始取得指定長度的字元，如未指定限制長度，即回傳位移值後的所有字元。 -
(b) -x 運算子
檢查此路徑是否存在。
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Script 2
#! /bin/bash if [ $# -ne 1] ; then # (d) # (f) echo "" > &2 exit 1 fi check4_cmd_in_path "$1" case $? in # (c) 0) echo "exit cmd in path" ;; 1) echo "can not found out cmd in path, which remains in doubt." ;; 2) echo "cmd not exit in path" ;; esac exit 0 -
Syntax
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(c) 變數切割法 $?
此為正規表示法，即第一字元，如 -c1 -
(d) 變數切割方法 #
用來刪除符合比對模板的第一組實體。 -
(e) 變數擷取方法 %
符合比對模板的內容之後遺留下來的結果。 -
(f) -ne or -eq
-n means not equal -eq means equal
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Execution Scripts
Before Execution, plz add absolute path in env var and execute the shell script in this way...
$ inpath echo
echo 存在於路徑清單中
(to be continued...)
All related with DBMoonLab
