Linux 学习笔记

                                                Linux 学习笔记

 

#!/bin/bash
echo "---for---";
for i in {a..c};
do
  echo $i;
done;
for ((i=0; i<3; i++)) {
  echo $i;
}
echo "---while---";
num=5;
while [ $num -gt 0 ];
do
  echo $num;
  let num--;
done;
echo "---until---";
x=0;
until [ $x -eq 5 ];
do
  let x++;
  echo $x;
done;
echo "---if---";
echo `[ 55555 -eq 5 ]`;
FILE_PATH="/home/guardian/test/ifs.sh";
if [ -f $FILE_PATH ]; then
   echo File exists;
else
   echo File dose not exist;
fi;
STR1="HEHE";
STR2="HAHA";
if [[ $STR1 = $STR2  ]]; then
   echo "两个字符串相等";
else
   echo "两个字符串不相等";
fi;
if [ -z $STR1 ]; then
   echo "字符串为空!";
else
   echo "字符串不为空!";
fi;
STR3="";
if [[ -n $STR1 ]] && [[ -z $STR3  ]];
then
   echo STR1 is noneempty and STR3 is empty string.
fi;