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      400-650-7353
      ڵλã > IT؛Y > linux > LinuxA֪RshellַҊ

      LinuxA֪RshellַҊ

      • Դ͘I
      • 2021-09-28 10:42:00
      • x()
      • ֙C

      ַݽȡ

      Ƚ

      ${׃:ʼλ:L}

      lȡַ12345678905λ8λ

      [root@host01 ~]# x="1234567890"

      [root@host01 ~]# echo ${x:4:4}

      5678

      lȡַ12345678903λһλ

      [root@host01 ~]# x="1234567890"

      [root@host01 ~]# echo ${x:2}

      34567890

      [root@host01 ~]# x="1234567890"

      [root@host01 ~]# echo ${#x}

      10

      [root@host01 ~]# echo ${x:2:${#x}}

      34567890

      ȡַ1234567890ǰ5λ

      [root@host01 ~]# x="1234567890"

      [root@host01 ~]# echo ${x:0:5}

      12345

      [root@host01 ~]# echo ${x::5}

      12345

      lȡַ“A񹲺͇”ĵ3λ4λ

      [root@host01 ~]# x="A񹲺͇"

      [root@host01 ~]# echo ${x:2:2}

      ҂Ƚ

      ${׃:0-ʼλ:L}

       ҂Ƚȡַ“A񹲺͇”҂ȵ3λһλ

      [root@host01 ~]# x="A񹲺͇"

      [root@host01 ~]# echo ${x:0-3}

      ͇

      ҂Ƚȡַ“A񹲺͇”҂ȵ3λ_ʼȡ2λ

      [root@host01 ~]# x="A񹲺͇"

      [root@host01 ~]# echo ${x:0-3:2}

      ַ1234567890߅5λ_ʼȡ3λ

      [root@host01 ~]# x="1234567890"

      [root@host01 ~]# echo ${x:5:3}

      678

      ַQ

      1. ֻQһƥY${׃/old/new}

      ַ1234512345Ќһ3Qxxx

      [root@backup ~]# i="1234512345"

      [root@backup ~]# echo ${i/3/xxx}

      12xxx4512345

      2. QȫƥY${׃//old/new}

      ַ1234512345Ќе3Qxxx

      [root@backup ~]# i="1234512345"

      [root@backup ~]# echo ${i//3/xxx}

      12xxx4512xxx45

      ַ1234512345Ќе3Qɿַ

      [root@backup ~]# i="1234512345"

      [root@backup ~]# echo ${i//3/}

      12451245

      ַ݄h

      1. ƥh${׃#*PI~}

      ַhttp://www.sina.com.cnЌð̖“:”߅ַȥ

      [root@backup ~]# i="http://www.sina.com.cn"

      [root@backup ~]# echo ${i#*:}

      //www.sina.com.cn

      ַhttp://www.sina.com.cnЌһ“.”߅ַȥ

      [root@backup ~]# i="http://www.sina.com.cn"

      [root@backup ~]# echo ${i#*.}

      sina.com.cn

      2. Lƥh${׃##*PI~}

      ַhttp://www.sina.com.cnЌ“http://”߅ַȥ

      [root@backup ~]# i="http://www.sina.com.cn"

      [root@backup ~]# echo ${i##*\/}

      www.sina.com.cn

      ַhttp://www.sina.com.cnЌһ“.”߅ַȥ

      [root@backup ~]# i="http://www.sina.com.cn"

      [root@backup ~]# echo ${i##*.}

      cn

      ַhttp://www.sina.com.cnЌһ“w”߅ַȥ

      [root@backup ~]# i="http://www.sina.com.cn"

      [root@backup ~]# echo ${i##*w}

      .sina.com.cn

      3. ƥh${׃%PI~*}

      ַhttp://www.sina.com.cnЌ߅һ“.”߅ַȥ

      [root@backup ~]# i="http://www.sina.com.cn"

      [root@backup ~]# echo ${i%.*}

      http://www.sina.com

      Ӌ㮔ǰűP“/”օ^ĴűPʹ

      [root@backup ~]# df

      Filesystem 1K-blocks Used Available Use% Mounted on

      devtmpfs 487168 0 487168 0% /dev

      tmpfs 497828 0 497828 0% /dev/shm

      tmpfs 497828 7636 490192 2% /run

      tmpfs 497828 0 497828 0% /sys/fs/cgroup

      /dev/sda3 11523072 1674024 9849048 15% /

      /dev/sda1 520868 156640 364228 31% /boot

      tmpfs 99568 0 99568 0% /run/user/0

      t֘R15%ȡxֵo׃i

      [root@backup ~]# df|grep "/$"

      /dev/sda3 11523072 1674100 9848972 15% /

      [root@backup ~]# df|grep "/$"|awk '{print $5}'

      15%

      [root@backup ~]# i=$(df|grep "/$"|awk '{print $5}')

      [root@backup ~]# echo $i

      15%

      ַ“15%”е“%”ȥ

      [root@backup ~]# echo ${i%\%*}

      15

      4. Lƥh${׃%%PI~}

      ַhttp://www.sina.com.cnЌ߅һ“.”߅ַȥ

      [root@backup ~]# i="http://www.sina.com.cn"

      [root@backup ~]# echo ${i%%.*}

      http://www

      ַ׃ʼֵ̎

      ʹecho ${׃:-ֵ}ķʽݔ׃ֵ׃ھݔھݔO“ֵ”

      ׃xӡ׃xֵ;׃xڴӡOֵ

      [root@host01 ~]# x="1234567890"

      [root@host01 ~]# echo ${x:-abc}

      1234567890

      [root@host01 ~]# unset x

      [root@host01 ~]# echo ${x:-abc}

      abc

      ¡LinuxA֪RshellַҊю

      >>ĵַhttp://www.threeriversmusicproducts.com/zhuanye/2021/70185.html

      THE END  

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