for DEMO

举例一：

[xiluhua@vm-xiluhua][~/shell_script]$ cat forDemo1.sh
#=======================================================================================
#/bin/bash
#auth: xiluhua
#date: 20160717
#desc: print file list in a directory
#=======================================================================================
 
[ -z $1 ] && echo "exception@1: directory can not be null" && exit 1
 
echo "prompt: print file list in a directory ..."
for file in $(ls $1/*.123)
do 
        echo $file
done
exit 0

举例二：

[xiluhua@vm-xiluhua][~/shell_script]$ cat forDemo2.sh 
#=======================================================================================
#/bin/bash
#auth: xiluhua
#date: 20160717
#desc: print triangle with *
#=======================================================================================
 
for (( i=0; i<3; i++ ))
do
    let space=2-$i
        #echo $space
        for (( j=0; j<${space}; j++ ))
        do
                printf " "
        done
 
        let star=2*$i+1
        for (( k=0; k<$star; k++ ))
    do
        printf "*"
    done
 
        echo ""
done