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        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

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