The simplest way to “subtrack” a string variable in terminal?












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Let's assume that we've a variable $test which holds a value asd 123 - what is the most simplest way to cut, for example, asd part?



I've googled this for awhile and surprised that I couldn't find an answer.










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    1















    Let's assume that we've a variable $test which holds a value asd 123 - what is the most simplest way to cut, for example, asd part?



    I've googled this for awhile and surprised that I couldn't find an answer.










    share|improve this question

























      1












      1








      1








      Let's assume that we've a variable $test which holds a value asd 123 - what is the most simplest way to cut, for example, asd part?



      I've googled this for awhile and surprised that I couldn't find an answer.










      share|improve this question














      Let's assume that we've a variable $test which holds a value asd 123 - what is the most simplest way to cut, for example, asd part?



      I've googled this for awhile and surprised that I couldn't find an answer.







      command-line






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      asked Jan 4 at 6:03









      Cecily MillerCecily Miller

      10115




      10115






















          1 Answer
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          In Bourne-like shells, such as dash ( /bin/sh on Ubuntu ), bash and ksh there is something known as parameter expansion, and is a feature specified by POSIX standard. Specifically, to quote dash manual:



           ${parameter%word}     Remove Smallest Suffix Pattern.  The word is expanded to produce a pattern.  The parameter expansion then results in parameter, with the smallest
          portion of the suffix matched by the pattern deleted.

          ${parameter%%word} Remove Largest Suffix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
          portion of the suffix matched by the pattern deleted.

          ${parameter#word} Remove Smallest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the smallest
          portion of the prefix matched by the pattern deleted.

          ${parameter##word} Remove Largest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
          portion of the prefix matched by the pattern deleted.


          Thus, to replace asd part you can do:



          $ var="asd 123"
          $ echo ${var#asd*}
          123


          To remove 123 you can do:



          $ echo ${var%*123}
          asd


          bash goes even further with this with another form: ${parameter/string/replacement} and ${parameter//string/replacement}. First one replaces first occurrence of string. Second form replaces all occurrences. For instance:



          $ echo ${var//123/}
          asd
          $ echo ${var//asd/}
          123


          Note that according with the syntax, the replacement part is empty string






          share|improve this answer























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            1 Answer
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            1 Answer
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            active

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            active

            oldest

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            active

            oldest

            votes









            2














            In Bourne-like shells, such as dash ( /bin/sh on Ubuntu ), bash and ksh there is something known as parameter expansion, and is a feature specified by POSIX standard. Specifically, to quote dash manual:



             ${parameter%word}     Remove Smallest Suffix Pattern.  The word is expanded to produce a pattern.  The parameter expansion then results in parameter, with the smallest
            portion of the suffix matched by the pattern deleted.

            ${parameter%%word} Remove Largest Suffix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
            portion of the suffix matched by the pattern deleted.

            ${parameter#word} Remove Smallest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the smallest
            portion of the prefix matched by the pattern deleted.

            ${parameter##word} Remove Largest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
            portion of the prefix matched by the pattern deleted.


            Thus, to replace asd part you can do:



            $ var="asd 123"
            $ echo ${var#asd*}
            123


            To remove 123 you can do:



            $ echo ${var%*123}
            asd


            bash goes even further with this with another form: ${parameter/string/replacement} and ${parameter//string/replacement}. First one replaces first occurrence of string. Second form replaces all occurrences. For instance:



            $ echo ${var//123/}
            asd
            $ echo ${var//asd/}
            123


            Note that according with the syntax, the replacement part is empty string






            share|improve this answer




























              2














              In Bourne-like shells, such as dash ( /bin/sh on Ubuntu ), bash and ksh there is something known as parameter expansion, and is a feature specified by POSIX standard. Specifically, to quote dash manual:



               ${parameter%word}     Remove Smallest Suffix Pattern.  The word is expanded to produce a pattern.  The parameter expansion then results in parameter, with the smallest
              portion of the suffix matched by the pattern deleted.

              ${parameter%%word} Remove Largest Suffix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
              portion of the suffix matched by the pattern deleted.

              ${parameter#word} Remove Smallest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the smallest
              portion of the prefix matched by the pattern deleted.

              ${parameter##word} Remove Largest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
              portion of the prefix matched by the pattern deleted.


              Thus, to replace asd part you can do:



              $ var="asd 123"
              $ echo ${var#asd*}
              123


              To remove 123 you can do:



              $ echo ${var%*123}
              asd


              bash goes even further with this with another form: ${parameter/string/replacement} and ${parameter//string/replacement}. First one replaces first occurrence of string. Second form replaces all occurrences. For instance:



              $ echo ${var//123/}
              asd
              $ echo ${var//asd/}
              123


              Note that according with the syntax, the replacement part is empty string






              share|improve this answer


























                2












                2








                2







                In Bourne-like shells, such as dash ( /bin/sh on Ubuntu ), bash and ksh there is something known as parameter expansion, and is a feature specified by POSIX standard. Specifically, to quote dash manual:



                 ${parameter%word}     Remove Smallest Suffix Pattern.  The word is expanded to produce a pattern.  The parameter expansion then results in parameter, with the smallest
                portion of the suffix matched by the pattern deleted.

                ${parameter%%word} Remove Largest Suffix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
                portion of the suffix matched by the pattern deleted.

                ${parameter#word} Remove Smallest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the smallest
                portion of the prefix matched by the pattern deleted.

                ${parameter##word} Remove Largest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
                portion of the prefix matched by the pattern deleted.


                Thus, to replace asd part you can do:



                $ var="asd 123"
                $ echo ${var#asd*}
                123


                To remove 123 you can do:



                $ echo ${var%*123}
                asd


                bash goes even further with this with another form: ${parameter/string/replacement} and ${parameter//string/replacement}. First one replaces first occurrence of string. Second form replaces all occurrences. For instance:



                $ echo ${var//123/}
                asd
                $ echo ${var//asd/}
                123


                Note that according with the syntax, the replacement part is empty string






                share|improve this answer













                In Bourne-like shells, such as dash ( /bin/sh on Ubuntu ), bash and ksh there is something known as parameter expansion, and is a feature specified by POSIX standard. Specifically, to quote dash manual:



                 ${parameter%word}     Remove Smallest Suffix Pattern.  The word is expanded to produce a pattern.  The parameter expansion then results in parameter, with the smallest
                portion of the suffix matched by the pattern deleted.

                ${parameter%%word} Remove Largest Suffix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
                portion of the suffix matched by the pattern deleted.

                ${parameter#word} Remove Smallest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the smallest
                portion of the prefix matched by the pattern deleted.

                ${parameter##word} Remove Largest Prefix Pattern. The word is expanded to produce a pattern. The parameter expansion then results in parameter, with the largest
                portion of the prefix matched by the pattern deleted.


                Thus, to replace asd part you can do:



                $ var="asd 123"
                $ echo ${var#asd*}
                123


                To remove 123 you can do:



                $ echo ${var%*123}
                asd


                bash goes even further with this with another form: ${parameter/string/replacement} and ${parameter//string/replacement}. First one replaces first occurrence of string. Second form replaces all occurrences. For instance:



                $ echo ${var//123/}
                asd
                $ echo ${var//asd/}
                123


                Note that according with the syntax, the replacement part is empty string







                share|improve this answer












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                answered Jan 4 at 6:46









                Sergiy KolodyazhnyySergiy Kolodyazhnyy

                70.6k9147310




                70.6k9147310






























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