第一部分 Shell基础编程——第三章 Shell输入和输出

r囧r小猫 2022-03-19 08:40 263阅读 0赞

### 笔记 ###

#Shell输入和输出
    
    #echo：显示文本行活变量，或者把字符串输入到文件，默认回车换行
    #\c：回车不换行
    #\f：禁止
    #\t：跳格，相当于按了一个Tab键
    #\n：回车换行
    
    #更名
    #sudo mv edhod.sh echod
    #改变权限
    #chmod 755 echod
    
    #cat echod
    #!/bin/bash
    #echod
    echo -e "This echo's 3 new lines\n\n\n"
    echo "ok"
    echo
    echo "This echo's 3 new lines\n\n\n"
    echo "The log files have all been done">mylogfile.txt
    
    #创mylogfile.txt文件
    sudo touch mylogfile.txt
    
    #执行（-e解析特殊字符）
    ./echod
    This echo's 3 new lines
    
    
    
    ok
    
    This echo's 3 new lines\n\n\n
    
    #演示回车换行和回车不换行
    [root@localhost 0330]# cat mylogfile.txt
    The log files have all been done
    
    #回车换行
    [root@localhost 0330]# echo "The log files have all been done"                  Th log files have all been done
    
    #回车不换行
    [root@localhost 0330]# echo -n "The log files have all been done"
    The log files have all been done[root@localhost 0330]#
    
    #read
    #read语句可以从键盘或者文件的某一行文本中读入信息，并将其赋给一个变量
    #vi readname
    chmod 755 readname
    [root@localhost 0330]# ./readname
    First Name:Chinaitlab
    Last Name:Shen zhen
    Your First Name is:Chinaitlab
    
    Your Last Name is:Shen zhen
    
    #演示以空格作为分隔符
    [root@localhost 0330]#
    cat  readname
    #!/bin/bash
    #readname
    echo -n "First Name:"
    read firstname
    echo -n "Last Name:"
    read lastname subname
    echo -e "Your First Name is:${firstname}\n"
    echo -e "Your Last Name is:${lastname}\n"
    echo -e "Your Subname is:${subname}\n"
    [root@localhost 0330]# ./readname
    First Name:chinaitlab
    Last Name:shen zhen
    Your First Name is:chinaitlab
    
    Your Last Name is:shen
    
    Your Subname is:zhen
    
    #cat
    man cat
    #单独显示myfile内容
    cat myfile
    
    #显示myfile1 myfile2 myfile3的内容
    [root@localhost 0330]# cat myfile1 myfile2 myfile3
    this is myfile1
    this is myfile2
    this is myfile3
    
    #将myfile1 myfile2 myfile3重定向到myfile123
    [root@localhost 0330]# cat myfile1 myfile2 myfile3 > myfile123
    [root@localhost 0330]# cat myfile123
    this is myfile1
    this is myfile2
    this is myfile3
    
    #dos传输的文本
    cat -v dos.txt
    
    #不会分页显示
    ls -l /bin > ls.txt
    cat ls.txt
    
    #分页显示方法一
    cat ls.txt | more
    
    #分页显示方法二
    cat ls.txt | less
    
    #分页显示方法三
    less ls.txt
    
    #分页显示方法四
    more ls.tx
    
    #管道(|)
    
    #分页显示
    #cat ls.txt | more
    
    #查找myfile
    #ls -l | grep "myfile"
    
    #显示分区信息
    #df –k
    
    #打印第一列分区信息
    #df -k | awk '{print $1}'
    
    #过滤掉Filesystem
    #df -k | awk '{print $1}' | grep -v "Filesystem"
    
    #tee
    #把输出的一个副本输送到标准输出，另一个副本拷贝到相应的文件中
    [root@localhost 0330]# who | tee who.out
    root     pts/0        Mar 30 19:00 (192.168.223.1)
    [root@localhost 0330]# who | tee who.out
    [root@localhost 0330]# cat who.out
    root     pts/0        Mar 30 19:00 (192.168.223.1)
    [root@localhost 0330]# who | tee -a who.out
    root     pts/0        Mar 30 19:00 (192.168.223.1)
    [root@localhost 0330]# cat who.out
    root     pts/0        Mar 30 19:00 (192.168.223.1)
    root     pts/0        Mar 30 19:00 (192.168.223.1)
    
    #将分区内容打印到屏幕并写入到文件
    [root@localhost 0330]# df -k | awk '{print $1}' | grep -v "Filesystem" | tee partation.txt
    /dev/sda2
    /dev/sda1
    none
    .host:/
    [root@localhost 0330]# cat partation.txt
    /dev/sda2
    /dev/sda1
    none
    .host:/
    
    #标准输入、输出和错误
    #标准输入 0 缺省键盘
    #标准输出 1 缺省屏幕
    #标准错误 2 缺省屏幕
    
    #文件重定向
    #> 重定向新文件
    #>> 追加
    
    [root@localhost 0330]# cat file
    jenny
    john
    wendy
    annie
    marry
    jack
    
    #将排序内容重定向到sort.out
    [root@localhost 0330]# cat file | sort 1>sort.out
    [root@localhost 0330]# cat sort.out
    annie
    jack
    jenny
    john
    marry
    wendy 
    
    #cat file | sort >sort.out等价于cat file | sort 1>sort.out
    
    #演示追加
    [root@localhost 0330]# cat path.out
    /home/wgb/shell/0330
    [root@localhost 0330]# pwd>>path.out
    [root@localhost 0330]# cat path.out
    /home/wgb/shell/0330
    /home/wgb/shell/0330
    #巧妙创建文件
    [root@localhost 0330]# ls -al nullfile
    ls: nullfile: No such file or directory
    [root@localhost 0330]# >nullfile
    [root@localhost 0330]# ls -al nullfile
    -rw-r--r--    1 root     root            0 Mar 30 19:36 nullfile
    
    #
    [root@localhost 0330]# sort <file
    annie
    jack
    jenny
    john
    marry
    wendy
    [root@localhost 0330]# cat name.txt
    chinaitlab
    shenzhen
    #将name.txt的内容作为输入传递给sort并将排序结果输出到name.out
    [root@localhost 0330]# sort< name.txt >name.out
    [root@localhost 0330]# cat name.out
    chinaitlab
    shenzhen
    
    #终止符，输入某个输入终止输入
    [root@localhost 0330]# cat term.txt
    this is a test
    [root@localhost 0330]# cat >>term.txt <<CHINAITLAB
    > Hello,there I am using a $TERM terminal
    > and my username is $LOGNAME
    > BYE ...
    > CHINAITLAB
    [root@localhost 0330]# cat term.txt
    this is a test
    Hello,there I am using a xterm terminal
    and my username is root
    BYE ...
    
    #将错误内容重定向到文件
    [root@localhost 0330]# grep "trident" missiles
    grep: missiles: No such file or directory
    [root@localhost 0330]# ls -al missile 2> err_message.txt
    [root@localhost 0330]# cat err_message.txt
    ls: missile: No such file or directory
    #/dev/null：无底洞
    
    #将错误内容抛出
    [root@localhost 0330]# grep "trident" missiles 2>/dev/null
    cat /dev/null
    
    #显示account_new.txt account_old.txt的内容，将标准输入到accounts.out，错误输出到accounts_err
    [root@localhost 0330]# cat account_new.txt account_old.txt 1>accounts.out 2>accounts_err
    [root@localhost 0330]# cat account_new.txt
    account_old.txt 1>accounts.out 2>accounts.err
    [root@localhost 0330]# cat account_old.txt
    cat: account_old.txt: No such file or directory
    [root@localhost 0330]# cat accounts.out
    account_old.txt 1>accounts.out 2>accounts.err
    [root@localhost 0330]# ls -al account_old.txt
    ls: account_old.txt: No such file or directory
    [root@localhost 0330]# cat accounts_err
    cat: account_old.txt: No such file or directory
    [root@localhost 0330]# cat account.err
    cat: account.err: No such file or directory
    
    
    #合并标准输出和标准错误
    [root@localhost 0330]# grep "standard" standard.txt > grep.out 2>&1
    [root@localhost 0330]# cat grep.out
    grep: standard.txt: No such file or directory
    vi standard.txt
    [root@localhost 0330]# cat standard.txt
    china it lab
    shen zhen
    standard shell
    bash
    linux shell
    redhat
    [root@localhost 0330]# grep "standard" standard.txt > grep.out 2>&1
    [root@localhost 0330]# cat grep.out
    standard shell
    
    
    #exec
    exec ./helloworld.sh
    #重启Shell
    
    #重新登录并设置环境变量
    [root@localhost root]# export CHINAITLAB=ShenZhen
    [root@localhost root]# echo $CHINAITLAB
    ShenZhen
    
    #再次执行脚本，再次打印刚才设置的环境变量时无内容
    exec ./helloworld.sh
    echo $CHINAITLAB
    
    #文件描述符（exec和文件描述符结合使用不会重启Shell）
    [root@localhost 0330]# vi file_desc
    [root@localhost 0330]# cat file_desc
    #!/bin/bash
    #file_desc
    exec 3<&0 0<name.txt
    read line1
    read line2
    exec 0<&3
    echo $line1
    echo $line2
    [root@localhost 0330]# vi name.txt
    [root@localhost 0330]# chmod 755 file_desc
    [root@localhost 0330]# cat name.txt
    chinaitlab
    shenzhen
    [root@localhost 0330]# ./file_desc
    chinaitlab
    shenzhen

### 附图 ###

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[1364646930_2181.jpg]: https://img-my.csdn.net/uploads/201303/30/1364646930_2181.jpg
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