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












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.






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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.






    command-line







    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.






      command-line







      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




      command-line






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Jan 4 at 6:03









      Cecily MillerCecily Miller

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      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












                share|improve this answer



                share|improve this answer










                answered Jan 4 at 6:46









                Sergiy KolodyazhnyySergiy Kolodyazhnyy

                71.3k9147313




                71.3k9147313






























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