bash 基本技巧

整理汇总从网上、书上看到的bash脚本的基本技巧，实验记录。

1. select 语句与异常处理

修改/etc/hosts文件增加3条记录

127.0.0.1       server01.demo.com127.0.0.1       server02.demo.com127.0.0.1       server03.demo.com

用ssh-keygen -t rsa 生产密钥，并用cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys发布

demo10.sh

#!/bin/bashservers=(        "server01.demo.com"        "server02.demo.com"        "server03.demo.com"        "QUIT")PS3="connect to the server?"select server in "${servers[@]}"; do    if [[ -z $server ]]; then        echo "select the number"        continue    fi    if [[ $server == "QUIT" ]]; then       echo "quit!"       exit 0    fi    echo "connect $server"    ssh "$server"done

oliver@bigdatadev:~/_src/shell$ ./demo10.sh1) server01.demo.com  3) server03.demo.com2) server02.demo.com  4) QUITconnect to the server?1connect server01.demo.comWelcome to Ubuntu 14.04.3 LTS (GNU/Linux 3.19.0-25-generic x86_64) * Documentation:  https://help.ubuntu.com/*** 需要重启系统 ***Last login: Sun Jul 24 17:15:33 2016 from localhostoliver@bigdatadev:~$ exit注销Connection to server01.demo.com closed.connect to the server?4quit!oliver@bigdatadev:~/_src/shell$ 

2. 配置文件、管道处理重复操作（管理多台机器）

#!/bin/bashservers=(        "server01.demo.com"        "server02.demo.com"        "server03.demo.com")for server in ${servers[@]}; do    ssh "$server" "$@"done

oliver@bigdatadev:~/_src/shell$ demo11.sh hostnamebigdatadevbigdatadevbigdatadevoliver@bigdatadev:~/_src/shell$ 

配置文件和管道 

$@参数列表、sed 在每行开头增加服务器名、&并发执行，wait等待完成，用group提取输出

运行脚本是利用< servers.txt 实现输入，>output.txt输出

#!/bin/bashwhile read server; do    ssh -n "$server" "$@" 2>&1 | sed "s/^/$server: /" &donewait

oliver@bigdatadev:~/_src/shell$ ./demo12.sh "vmstat 1 5" < servers.txt > output.txtoliver@bigdatadev:~/_src/shell$ grep "server01" < output.txtserver01.demo.com: procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----server01.demo.com:  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa stserver01.demo.com:  4  1      0 2114224  92244 1106820    0    0    85    53   76  283  2  1 97  1  0server01.demo.com:  2  0      0 2114252  92244 1106876    0    0     0     0   57  203  0  0 99  1  0server01.demo.com:  2  0      0 2114252  92244 1106876    0    0     0     0   55  172  0  1 99  0  0server01.demo.com:  2  0      0 2114252  92244 1106876    0    0     0     0   50  170  1  0 99  0  0server01.demo.com:  4  0      0 2114252  92244 1106876    0    0     0     0   44  159  0  1 99  0  0oliver@bigdatadev:~/_src/shell$ 

在脚本中处理重定向文件输入

#!/bin/bashfile=$1shiftwhile read server; do    ssh -n "$server" "$@" 2>&1 | sed "s/^/$server: /" &done <"$file"wait

oliver@bigdatadev:~/_src/shell$ ./demo13.sh servers.txt free: ssh: Could not resolve hostname : No address associated with hostnameserver02.demo.com:              total       used       free     shared    buffers     cachedserver02.demo.com: Mem:       4039084    1924268    2114816      14640      92376    1106892server02.demo.com: -/+ buffers/cache:     725000    3314084server02.demo.com: Swap:      3905532          0    3905532server03.demo.com:              total       used       free     shared    buffers     cachedserver03.demo.com: Mem:       4039084    1921456    2117628      14640      92376    1106892server03.demo.com: -/+ buffers/cache:     722188    3316896server03.demo.com: Swap:      3905532          0    3905532server01.demo.com:              total       used       free     shared    buffers     cachedserver01.demo.com: Mem:       4039084    1921192    2117892      14640      92376    1106892server01.demo.com: -/+ buffers/cache:     721924    3317160server01.demo.com: Swap:      3905532          0    3905532oliver@bigdatadev:~/_src/shell$ 

3. 进程监控

#!/bin/bashfunction monitor{    pgrep -x $1 >/dev/null 2>&1    return $?}if monitor "httpd"; then    status="up"else    status="down"fiwhile [[ true ]]; do    monitor "httpd"    rc=$?    if [[ $rc -eq 0 && $status != "up" ]]; then        status="up"        logger -t "my_monitor" "httpd is up."    fi    if [[ $rc -ne 0 && $status != "down" ]]; then        status="down"        logger -t "my_monitor" "httpd is down."    fi    sleep 10done

4. rsync、tee和mail

使用rsync备份、tee输出到文件和管道、mail发邮件，{}将命令放在一起重定向输出。

#!/bin/bashTEMPFILE=/tmp/snashot.log.$${    echo "=== Rsync from /data/ to snapshot/: ${data}"    mount -o rw, remount /dev/sdc    rsync -av /data/ /snapshot/    rc=$?    mount -o ro,remount /dev/sdc    if [[ $rc -eq 0 ]]; then        echo "=== Snapshot succeded: ${date}"        SUBJECT="Snapshot report {Succeeded}:    else        echo "=== Snapshot failed with rc=$rc: ${date}:        SUBJECT="Snapshot report {Failed}"    fi} 2>&1 | tee $TMPFILE | logger -t "snapshot"iconv -f utf8 -t gb2312  $TMPFILE | mail -s "$SUBJECT" [e-mail]