bash基础

################
#!/bin/bash
a=1000
b=2000
c=1000
if [ $a -eq $b ]
   then 
        echo "a=b"
elif [ $a -eq $c ]
   then
        echo "a=c"
else
   echo "b!=c"
fi
#################
read a1
case $a1 in
"1")
echo "1"
;;
"2")
echo "22"
;;
*)
echo "333"
;;
esac
##################
a2=1
while [ $a2 -lt 100 ]
do
clear
echo "this is $a2"
a3=1
while [ $a3 -lt 10 ]
do
a3=expr $a3 + 1
done
a2=expr $a2 + 1
done
################
for s in a b c d
do 
echo "$s"
sleep 1
done
###############
for (( i = 0; i < 10; i++)); do echo $i; done;
###############
read s a b
echo "111"
while [ $s -eq 3 ]
        do
        echo "ssss"
                while [ $a -eq 3 ]
                        do
                        echo "222"
                        echo "this is $a"
                        s=expr $s + 1
                        if [ $b -eq 3 ]
                                then
                                continue
                                echo "yyyyy"
                                else
                                echo "this is no"
                                break
                                echo "this is break1"
                        fi
                        echo "this is break2"
                        echo "$s"
                        done
        echo "this is break3"
        done
############
#!/bin/bash
function sl
{
    if [ $# -ne 2]      #传入的参数小于2.
      then
        return 1
    else
        if [ $1 -eq "test1" ] && [ $2 -eq test2 ]
            then
              return 0
            else
              return 2
        fi
    fi
}
sl test1 test2
case $? in             #传入返回的值.
"0")
echo "ok"
;;
"1")
echo "x x"
;;
"2")
echo "no"
;;
esac
############
gawk
sed
grep
cut
bash -v test.sh   #执行指令前显示出指令
bash -x test.sh        #执行指令后显示出指令
split -10000 csdn.txt  #把文件分成M行一个的N个文件
./test.sh &  #后台运行,登出后停止
nohup test.sh  #后台运行
jobs  #查看正在运行的程序
kill %1  #结束相应程序
export test1="testecho"  #配置环境变量
tr "[a-z]" "[A-Z]" < test1.txt >text2.txt  #大小写转换并存为text2.txt
ar  #创建备存文件
#数组
declare -a arr  #可省略
arr=(var0 var1 var2 var3)
echo "${arr[3]}"