How do you tell if a string contains another string in POSIX sh

Question

I want to write a Unix shell script that will do various logic if there is a string inside of another string  For example  if I am in a certain folder  branch off  Could someone please tell me how to accomplish this  If possible I would like to make this not shell specific  i e  not bash only  but if there s no other way I can make do with that      usr bin env sh  if     PWD  contains  String1    then     echo  String1 present  elif     PWD  contains  String2    then     echo  String2 present  else     echo  Else  fi

User · Answer

test   echo  stringcontain   ingcon   awk    print index  1   2      -gt 0  amp  amp  echo  String 1 contain string 2    --  output  String 1 contain string 2

User · Answer

Pure POSIX shell      bin sh CURRENT DIR  pwd   case   CURRENT DIR  in    String1   echo  String1 present        String2   echo  String2 present                  echo  else     esac   Extended shells like ksh or bash have fancy matching mechanisms  but the old-style case is surprisingly powerful

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case   pwd  in    path  echo  ends with path      path   echo  starts with path       path   echo  contains path         echo  this is the default    esac

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usr bin env sh    Searches a subset string in a string    1st arg reference string   2nd arg subset string to be matched  if echo   1    grep -q   2  then     echo   2 is in  1  else      echo   2 is not in  1  fi

User · Answer

If you want a ksh only method that is as fast as  test   you can do something like   contains     haystack needle       haystack   1  2       if      haystack  -ne    1      then         return 1     fi     return 0     It works by deleting the needle in the haystack and then comparing the string length of old and new haystacks

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Here s yet another solution  This uses POSIX substring parameter expansion  so it works in Bash  Dash  KornShell  ksh   Z shell  zsh   etc   test    string   word        string   amp  amp  echo   word found in  string    A functionalized version with some examples     contains string  substring      Returns 0 if the specified string contains the specified substring    otherwise returns 1  contains         string   1      substring   2      if test    string   substring        string      then         return 0       substring is in  string     else         return 1       substring is not in  string     fi    contains  abcd   e     echo  abcd does not contain e  contains  abcd   ab   amp  amp  echo  abcd contains ab  contains  abcd   bc   amp  amp  echo  abcd contains bc  contains  abcd   cd   amp  amp  echo  abcd contains cd  contains  abcd   abcd   amp  amp  echo  abcd contains abcd  contains        amp  amp  echo  empty string contains empty string  contains  a      amp  amp  echo  a contains empty string  contains     a     echo  empty string does not contain a  contains  abcd efgh   cd ef   amp  amp  echo  abcd efgh contains cd ef  contains  abcd efgh       amp  amp  echo  abcd efgh contains a space

User · Answer

Here is a link to various solutions of your issue   This is my favorite as it makes the most human readable sense   The Star Wildcard Method  if      string        substring       then     return 1 fi return 0

User · Answer

In special cases where you want to find whether a word is contained in a long text  you can iterate through the long text with a loop   found F query word this long string  many many words in this text  for w in  long string  do     if     w      query word     then           found T           break     fi done   This is pure Bourne shell

User · Answer

See the manpage for the  test  program   If you re just testing for the existence of a directory you would normally do something like so   if test -d  String1   then   echo  String1 present  end   If you re actually trying to match a string you can use bash expansion rules  amp  wildcards as well   if test -d  String    then   echo  A directory starting with  String  is present  end   If you need to do something more complex you ll need to use another program like expr

User · Answer

There s Bash regular expressions  Or there s  expr     if expr   link           gt   dev null  then     PRG   link    else     PRG  dirname   PRG     link    fi

User · Answer

Sadly  I am not aware of a way to do this in sh   However  using bash  starting in version 3 0 0  which is probably what you have   you can use the    operator like this      bin bash CURRENT DIR  pwd   if      CURRENT DIR      String1     then  echo  String1 present  elif      CURRENT DIR      String2     then  echo  String2 present  else  echo  Else  fi   As an added bonus  and or a warning  if your strings have any funny characters in them      accepts regexes as the right operand if you leave out the quotes

[shell] How do you tell if a string contains another string in POSIX sh?

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