Shell simple Use (-) judgment

Take a few simple examples of the judgments involved

1. Comparison of file-related judgments

#!/bin/Bashif[$#-lt1 ]     Then    Echo "No file name"Exit1elif[-D $1 ]     Then    Echo$1is directoryelif[-B $1 ]     Then         Echo$1is block deviceelif[-H $1 ]     Then        Echo$1Is linkfileelif[-C $1 ]     Then        Echo$1is character deviceelif[-F $1 ]     Then        Echo$1is normalfileElse     Echo "Don ' t recognize $"fiif[-R $1 ]     Then        Echo$1Is can readfiif[ -W$1 ]     Then         Echo$1IS canWritefiif[-X $1 ]     Then        Echo$1Is can excutefiif[-U $1 ]     Then        Echo$1Has SUID attributionfiif[-G $1 ]     Then        Echo$1Has SGID attributionfiif[-K $1 ]     Then        Echo$1Has Sticky bit attributionfiif[-S $1 ]     Then        Echo$1is a XXXfiExit0

The results of the implementation are as follows:

2. Number-related judgments

A.

#!/bin/Bashif[" $"-eq" $"]; Then# if[" $"-ne" $"]; Then    Echo$1Equal $2fiif[" $"-lt" $"]; Then# if[" $"-le" $"]; Then    Echo$1  Lessthan $2fiif[" $"-gt" $"]; Then# if[" $"-ge" $"]; Then    Echo$1Grate Then$2fi

B.

#!/bin/Bashread-P"Input The Age:" Age Case$ageinch    [0-9]| [1][0-2])        Echo " Child"        ;; [1][0-9])        Echo " Young"        ;; [2-5][0-9] )        Echo "Adult"        ;; [6-9][0-9])            Echo " Old"        ;; *    )        Echo "Not people"        ;;EsacExit0

The results of the implementation are as follows:

B.

#!/bin/Bash
Read-P"Iuput your Birthday (mmdd.ex> 0709):"Birnow=`Date+%m%d '
if["$bir"=="$now"]; Then 　　 Echo "Happy Birthday!!!"elif["$bir"-gt"$now"]; Then Year=`Date+%Y ' Total_d=$(($((`Date--Date="$year $bir"+%s '-'Date+%s '))/ -/ -/ -))Echo "Your birthday'll be $total _d later"Else Year=$((`Date+%y ' +1)) Total_d=$(($((`Date--Date="$year $bir"+%s '-'Date+%s '))/ -/ -/ -))Echo "Your birthday'll be $total _d later"fi

The results of the implementation are as follows:

3. String comparisons

#!/bin/Bashif[" $"==" $"]; Then# if[[" $"==" $"]]; Then    Echo$1Equal $2fiif[" $"!=" $"]; Then    Echo$1No equal $2fiif[[" $">" $"]]; Then# if[" $"\>" $"]; Then    Echo$1Grate Then$2fiif[[" $"<" $"]]; Then# if[" $"\<" $"]; Then    Echo$1  Less  Then$2fiif[-Z" $"]; Then    Echo$1is emptyfiif[-N" $"]; Then    Echo$1is no emptyfiif[[" $"==1* ]]; Then    Echo$1=="1*" 1111111111fiif[[" $"=="1*"]]; Then    Echo$1== \"1*\ "2222222222fi

The results of the implementation are as follows:

Two times comparison of 1*, pattern matching and full string matching, respectively

Shell simple Use (-) judgment