Shell编程(一）基础语法

#!/bin/bash

#$0: bash file name  with path
#$?: last cmd state after execute
#$*: all the param in form "param1param2pram3......"
#$@: all the param in form "param1""param2""param3""......"
#$#: param number
#$n: n corresponding to the param position

# =============== branch if example ==============

#eg0: string compare in branch
#-f: test file
#-s: test file lenth
#-d: test file dir
#-z: check zero file lenth
#string1 = string2:
#string1 != string2:
#string1  < string2:

dir=./test

if [ -d $dir ]
then
    echo "file exist"
else
    echo "file not exist"
fi;

if test -d $dir && [ -d $dir ]
then
    echo "yes"
else
    echo "no"
fi;

#eg1: string compare in branch
#-eq:
#-lt:
#-le:
#-gt:
#-ge:

tm=
tm2=ndl

if test -z "$tm"
then
    echo "yes"
else
    echo "no"
fi;

#eg3: int data compare in branch
t1=2
t2=2

if [ $t1  -lt $t2 ]; then
    echo "lt"
elif [ $t1  -eq $t2 ]; then
{ echo "eq";echo "test 1";
}
else
    echo "else"
fi

#eg4: int data compare in branch
if [ $# -lt 0 ]; then
    echo "$# lt zero"
elif [ $# -eq 0 ]; then
    echo "0"
elif [ $# -eq 1 ]; then
    echo $1
elif [ $# -eq 2 ]; then
    echo $1$2
elif [ $# -eq 3 ]; then
    echo $1$2$3
else
    echo others
fi;

# =============== branch case example ==============
#eg1:
echo "case test"
case $1 in
    *h | ?k) echo "0";;
    *o) echo " 1 | 2";;
    *) echo others;;
esac;

#eg2:
a=`date +%H`
echo $a

case $a in
    0[123456789] | 1[012]) echo "god morning";;
    1[3456789]) echo good afternoon ;;
    2[01234]) echo good evening;;
esac;

# =============== until example ==============

until grep "gavinhuang" /etc/passwd
do

    echo "hello world"

done;

# =============== loop for  example ==============

p=`pwd`
for dir in $p/test $p/test1
do
    echo $dir
    cd $dir

    for file in *.[c]
    do
        ls -l $file
    done;
done;

# =============== read example ==============
#read [param] value
#param : -t timeout
#param : -p prompt tittle

# =============== while example ==============

while read -p input:  number
do
case $number in
    [012345]?) echo no pass: $number;
                echo input a numbe\c;;
    [678]?) echo good: $number;
                echo input a numbe\c;;
    9? | 100) echo exe good: $number;
                echo input a numbe\c;;
    *) echo input err;
            echo input a numbe\c;;
esac;

done;

# =============== select example ==============
a1=Linux
a2="Mac Os"
a3=Windows
select var in "$a1" "$a2" "$a3"
do
    case $var in
        "$a1") echo choose option 1: $var;;
        "$a2") echo choose option 2: $var;;
        "$a3") echo choose option 3: $var;;
    esac;

break;
done;