7. Shell 脚本编写
1、提示用户输入一个字符串，如果是 hello，打出 yes，并每秒输出 "hello，world"，否则就输出 no，实现如下：
#!/bin/bash
#Filename:hello.sh
echo "Please input 'hello'"
read -p "> " str // 得到键盘输入
echo $str
if [ "$str" == hello ]
then
echo "yes"
while true
do
echo "hello, world"
sleep 1 // 睡眠1秒
done
else
echo "no"
fi
2、
实现一个 find.sh，运行 ./find.sh /tmp/test.txt ，当 /tmp/test.txt 为文件且存在时输出 yes, 否则输出 no，实现如下：
#!/bin/bash
#Filename:find.sh
args1=$1 ( $0 为要执行的文件路径，$1 为输入的第一个参数，以此类推)
if [ -e "$args1" ] // 如果该变量代表的值是一个文件
then
echo "yes"
else
echo "no"
fi
判断文件的参数如下：
-e 文件存在
-f file 是一个 regular 文件(不是目录或者设备文件)
-s 文件长度不为 0
-d 文件是个目录
-b 文件是个块设备(软盘,cdrom 等等)
-c 文件是个字符设备(键盘,modem,声卡等等)
-p 文件是个管道
-h 文件是个符号链接
-L 文件是个符号链接
-S 文件是个 socket
-t 关联到一个终端设备的文件描述符 这个选项一般都用来检测是否在一个给定脚本中的 stdin[-t0]或[-t1]是一个终端
-r 文件具有读权限(对于用户运行这个 test)
-w 文件具有写权限(对于用户运行这个 test)
-x 文件具有执行权限(对于用户运行这个 test)
-f file 是一个 regular 文件(不是目录或者设备文件)
-s 文件长度不为 0
-d 文件是个目录
-b 文件是个块设备(软盘,cdrom 等等)
-c 文件是个字符设备(键盘,modem,声卡等等)
-p 文件是个管道
-h 文件是个符号链接
-L 文件是个符号链接
-S 文件是个 socket
-t 关联到一个终端设备的文件描述符 这个选项一般都用来检测是否在一个给定脚本中的 stdin[-t0]或[-t1]是一个终端
-r 文件具有读权限(对于用户运行这个 test)
-w 文件具有写权限(对于用户运行这个 test)
-x 文件具有执行权限(对于用户运行这个 test)
3、
实现一个 ping.sh
- 运行 ./ping.sh start 后在后台运行 ping 命令，ping 127.0.0.1，并把 ping 结果输出到 /tmp/ping.log
- 运行 ./ping.sh status 显示 ping 命令是否正在运行
- 运行 ./ping.sh stop 停止 ping 命令，如果正在运行的话。
# 方法一：输入 stop 时，直接关闭所有的 ping 进程
#!/bin/bash
#Filaname:ping.sh
if [ "$1" == "start" ]
then
ping 127.0.0.1 > /tmp/ping.log &
elif [ "$1" == "status" ]
then
ps -ef | grep "ping 127.0.0.1"
elif [ "$1" == "stop" ]
then
killall ping (会干掉所有的ping 进程，包括子进程)
fi
#方法二：得到ping 127.0.0.1 的进程 ID ，再用kill 结束掉
#!/bin/bash
#Filaname:ping.sh
if [ "$1" == "start" ]
then
ping 127.0.0.1 > /tmp/ping.log &
elif [ "$1" == "status" ]
then
ps -ef | grep "ping 127.0.0.1"
elif [ "$1" == "stop" ]
then
pid=`ps -ef |grep ping | grep "127.0.0.1" | awk '{print $2}'`
if [ "pid" -gt 0 ];then
kill $pid
echo kill $pid
else
echo "要关闭的进程不存在"
fi
fi
3、将上面的 ping.sh 加入开机自启动
系统的rc.local 文件是在 系统启动之后才加载的，可以把脚本添加到这个文件中
打开 /etc/rc.d/rc.local 文件（root 用户）：vim /etc/rc.d/rc.local
加入下面两行：
cd /home/demon # 进入到当前目录
su demon -c "./ping.sh start"
4、解析 mysql.server 脚本的作用
mysql.server 是用来打开或关闭 mysql 服务
#!/bin/sh
basedir=
datadir=
service_startup_timeout=900 #服务启动超时时间
lockdir='/var/lock/subsys'
lock_file_path="$lockdir/mysql"
mysqld_pid_file_path=
# 判断 $basedir 的长度是否为 0
if test -z "$basedir"
then
basedir=/usr/local/mysql
bindir=/usr/local/mysql/bin
if test -z "$datadir"
then
datadir=/usr/local/mysql/data
fi
sbindir=/usr/local/mysql/bin
libexecdir=/usr/local/mysql/bin
else
bindir="$basedir/bin"
if test -z "$datadir"
then
datadir="$basedir/data"
fi
sbindir="$basedir/sbin"
libexecdir="$basedir/libexec"
fi
datadir_set=
lsb_functions="/lib/lsb/init-functions"
# 判断是否是一个文件，并存在
if test -f $lsb_functions ; then
. $lsb_functions
else
log_success_msg()
{
echo " SUCCESS! $@"
}
log_failure_msg()
{
echo " ERROR! $@"
}
fi
#添加 PATH 到环境变量中
PATH="/sbin:/usr/sbin:/bin:/usr/bin:$basedir/bin"
export PATH
# mode 是传入的第一个参数，用于判断启动脚本是 开启 mysql 服务，还是关闭
mode=$1 # start or stop
# 判断参数的数量是否大于 1
# $# 为参数的数量，-ge 大于(数字比较)，当 && 左边的表达式为真时，才会执行 右边的表达式，
# shift 表示左移，shift 2表示左移两个，&4 移到 &2，&3 移到 &1，原来的&1,、&2被丢弃吊了，而 &0 不会被影响；不带参数的相当于 shift 1
[ $# -ge 1 ] && shift
other_args="$*" # uncommon, but needed when called from an RPM upgrade action
# Expected: "--skip-networking --skip-grant-tables"
# They are not checked here, intentionally, as it is the resposibility
# of the "spec" file author to give correct arguments only.
case `echo "testing\c"`,`echo -n testing` in
*c*,-n*) echo_n= echo_c= ;;
*c*,*) echo_n=-n echo_c= ;;
*) echo_n= echo_c='\c' ;;
esac
parse_server_arguments() {
for arg do
case "$arg" in
--basedir=*) basedir=`echo "$arg" | sed -e 's/^[^=]*=//'`
bindir="$basedir/bin"
if test -z "$datadir_set"; then
datadir="$basedir/data"
fi
sbindir="$basedir/sbin"
libexecdir="$basedir/libexec"
;;
--datadir=*) datadir=`echo "$arg" | sed -e 's/^[^=]*=//'`
datadir_set=1
;;
--pid-file=*) mysqld_pid_file_path=`echo "$arg" | sed -e 's/^[^=]*=//'` ;;
--service-startup-timeout=*) service_startup_timeout=`echo "$arg" | sed -e 's/^[^=]*=//'` ;;
esac
done
}
wait_for_pid () {
verb="$1" # created | removed
pid="$2" # process ID of the program operating on the pid-file
pid_file_path="$3" # path to the PID file.
i=0
avoid_race_condition="by checking again"
while test $i -ne $service_startup_timeout ; do
case "$verb" in
'created')
# wait for a PID-file to pop into existence.
test -s "$pid_file_path" && i='' && break
;;
'removed')
# wait for this PID-file to disappear
test ! -s "$pid_file_path" && i='' && break
;;
*)
echo "wait_for_pid () usage: wait_for_pid created|removed pid pid_file_path"
exit 1
;;
esac
# if server isn't running, then pid-file will never be updated
if test -n "$pid"; then
if kill -0 "$pid" 2>/dev/null; then
: # the server still runs
else
# The server may have exited between the last pid-file check and now.
if test -n "$avoid_race_condition"; then
avoid_race_condition=""
continue # Check again.
fi
# there's nothing that will affect the file.
log_failure_msg "The server quit without updating PID file ($pid_file_path)."
return 1 # not waiting any more.
fi
fi
echo $echo_n ".$echo_c"
i=`expr $i + 1`
sleep 1
done
if test -z "$i" ; then
log_success_msg
return 0
else
log_failure_msg
return 1
fi
}
# Get arguments from the my.cnf file,
# the only group, which is read from now on is [mysqld]
# test -x 判断文件是否可执行
if test -x ./bin/my_print_defaults
then
print_defaults="./bin/my_print_defaults"
elif test -x $bindir/my_print_defaults
then
print_defaults="$bindir/my_print_defaults"
elif test -x $bindir/mysql_print_defaults
then
print_defaults="$bindir/mysql_print_defaults"
else
# Try to find basedir in /etc/my.cnf
conf=/etc/my.cnf
print_defaults=
# 判断文件是否可读
if test -r $conf
then
subpat='^[^=]*basedir[^=]*=\(.*\)$'
dirs=`sed -e "/$subpat/!d" -e 's//\1/' $conf`
for d in $dirs
do
d=`echo $d | sed -e 's/[ ]//g'`
if test -x "$d/bin/my_print_defaults"
then
print_defaults="$d/bin/my_print_defaults"
break
fi
if test -x "$d/bin/mysql_print_defaults"
then
print_defaults="$d/bin/mysql_print_defaults"
break
fi
done
fi
# Hope it's in the PATH ... but I doubt it
# 判断字符串长度是否为 0
test -z "$print_defaults" && print_defaults="my_print_defaults"
fi
#
# Read defaults file from 'basedir'. If there is no defaults file there
# check if it's in the old (depricated) place (datadir) and read it from there
#
extra_args=""
if test -r "$basedir/my.cnf"
then
extra_args="-e $basedir/my.cnf"
else
if test -r "$datadir/my.cnf"
then
extra_args="-e $datadir/my.cnf"
fi
fi
parse_server_arguments `$print_defaults $extra_args mysqld server mysql_server mysql.server`
#
# Set pid file if not given
#
if test -z "$mysqld_pid_file_path"
then
mysqld_pid_file_path=$datadir/`hostname`.pid
else
case "$mysqld_pid_file_path" in
/* ) ;;
* ) mysqld_pid_file_path="$datadir/$mysqld_pid_file_path" ;;
esac
fi
case "$mode" in
'start')
# Start daemon
# Safeguard (relative paths, core dumps..)
cd $basedir
echo $echo_n "Starting MySQL"
if test -x $bindir/mysqld_safe
then
# Give extra arguments to mysqld with the my.cnf file. This script
# may be overwritten at next upgrade.
$bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 &
wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?
# Make lock for RedHat / SuSE
if test -w "$lockdir"
then
touch "$lock_file_path"
fi
exit $return_value
else
log_failure_msg "Couldn't find MySQL server ($bindir/mysqld_safe)"
fi
;;
'stop')
# Stop daemon. We use a signal here to avoid having to know the
# root password.
if test -s "$mysqld_pid_file_path"
then
mysqld_pid=`cat "$mysqld_pid_file_path"`
if (kill -0 $mysqld_pid 2>/dev/null)
then
echo $echo_n "Shutting down MySQL"
kill $mysqld_pid
# mysqld should remove the pid file when it exits, so wait for it.
wait_for_pid removed "$mysqld_pid" "$mysqld_pid_file_path"; return_value=$?
else
log_failure_msg "MySQL server process #$mysqld_pid is not running!"
rm "$mysqld_pid_file_path"
fi
# Delete lock for RedHat / SuSE
if test -f "$lock_file_path"
then
rm -f "$lock_file_path"
fi
exit $return_value
else
log_failure_msg "MySQL server PID file could not be found!"
fi
;;
'restart')
# Stop the service and regardless of whether it was
# running or not, start it again.
if $0 stop $other_args; then
$0 start $other_args
else
log_failure_msg "Failed to stop running server, so refusing to try to start."
exit 1
fi
;;
'reload'|'force-reload')
if test -s "$mysqld_pid_file_path" ; then
read mysqld_pid < "$mysqld_pid_file_path"
kill -HUP $mysqld_pid && log_success_msg "Reloading service MySQL"
touch "$mysqld_pid_file_path"
else
log_failure_msg "MySQL PID file could not be found!"
exit 1
fi
;;
'status')
# First, check to see if pid file exists
if test -s "$mysqld_pid_file_path" ; then
read mysqld_pid < "$mysqld_pid_file_path"
if kill -0 $mysqld_pid 2>/dev/null ; then
log_success_msg "MySQL running ($mysqld_pid)"
exit 0
else
log_failure_msg "MySQL is not running, but PID file exists"
exit 1
fi
else
# Try to find appropriate mysqld process
mysqld_pid=`pidof $libexecdir/mysqld`
# test if multiple pids exist
pid_count=`echo $mysqld_pid | wc -w`
if test $pid_count -gt 1 ; then
log_failure_msg "Multiple MySQL running but PID file could not be found ($mysqld_pid)"
exit 5
elif test -z $mysqld_pid ; then
if test -f "$lock_file_path" ; then
log_failure_msg "MySQL is not running, but lock file ($lock_file_path) exists"
exit 2
fi
log_failure_msg "MySQL is not running"
exit 3
else
log_failure_msg "MySQL is running but PID file could not be found"
exit 4
fi
fi
;;
*)
# usage
basename=`basename "$0"`
echo "Usage: $basename {start|stop|restart|reload|force-reload|status} [ MySQL server options ]"
exit 1
;;
esac
exit 0
