Replace one substring for another string in shell script

Question

I have  I love Suzi and Marry  and I want to change  Suzi  to  Sara       bin bash firstString  I love Suzi and Marry  secondString  Sara    do something      The result must be like this   firstString  I love Sara and Marry

User · Answer

This can be done entirely with bash string manipulation:

first="I love Suzy and Mary"
second="Sara"
first=${first/Suzy/$second}

That will replace only the first occurrence; to replace them all, double the first slash:

first="Suzy, Suzy, Suzy"
second="Sara"
first=${first//Suzy/$second}
# first is now "Sara, Sara, Sara"

User · Answer

echo  string    sed  s  original   target  g      s  means  substitute   g  means  global  all matching occurrences

User · Answer

For Dash all previous posts aren t working The POSIX sh compatible solution is  result   echo  quot  firstString quot    sed  quot s Suzi  secondString  quot    This will replace the first occurrence on each line of input  Add a  g flag to replace all occurrences  result   echo  quot  firstString quot    sed  quot s Suzi  secondString g quot

User · Answer

Pure POSIX shell method  which unlike Roman Kazanovskyi s sed-based answer needs no external tools  just the shell s own native parameter expansions   Note that long file names are minimized so the code fits better on one line   f  I love Suzi and Marry  s Sara t Suzi      f  t         f     amp  amp  f    f  t   s  f   t   echo   f    Output   I love Sara and Marry     How it works    Remove Smallest Suffix Pattern      f  t    returns  I love  if the suffix  t  Suzi   is in  f  I love Suzi and Marry     But if t Zelda  then    f  t    deletes nothing  and returns the whole string  I love Suzi and Marry   This is used to test if  t is in  f with      f  t         f    which will evaluate to true if the  f string contains  Suzi   and false if not  If the test returns true  construct the desired string using Remove Smallest Suffix Pattern   f  t    I love  and Remove Smallest Prefix Pattern   f   t   and Marry   with the 2nd string  s  Sara  in between

User · Answer

To replace the first occurrence of a pattern with a given string  use   parameter pattern string       bin bash firstString  I love Suzi and Marry  secondString  Sara  echo    firstString Suzi  secondString         prints  I love Sara and Marry    To replace all occurrences  use   parameter  pattern string    message  The secret code is 12345  echo    message   0-9  X                prints  The secret code is XXXXX     This is documented in the Bash Reference Manual   sect 3 5 3  Shell Parameter Expansion     Note that this feature is not specified by POSIX  mdash  it s a Bash extension  mdash  so not all Unix shells implement it  For the relevant POSIX documentation  see The Open Group Technical Standard Base Specifications  Issue 7  the Shell  amp  Utilities volume   sect 2 6 2  Parameter Expansion

User · Answer

try this    sed  s Suzi  secondString g   lt  lt  lt   firstString

User · Answer

If tomorrow you decide you don t love Marry either she can be replaced as well   today    lt  tmp lovers txt  tomorrow    today  Suzi Sara   echo    tomorrow  Marry Jesica    gt   tmp lovers txt   There must be 50 ways to leave your lover

User · Answer

I know this is old but since no one mentioned about using awk       firstString  I love Suzi and Marry      echo  firstString   awk   gsub  Suzi   Sara    print

User · Answer

Since I can t add a comment    ruaka To make the example more readable write it like this  full string  I love Suzy and Mary  search string  Suzy  replace string  Sara  my string   full string  search string  replace string  or my string   full string Suzy Sarah

User · Answer

It s better to use bash than sed if strings have RegExp characters   echo   first string Suzi  second string    It s portable to Windows and works with at least as old as Bash 3 1   To show you don t need to worry much about escaping let s turn this    home name foo bar   Into this     foo bar   But only if  home name is in the beginning  We don t need sed   Given that bash gives us magic variables  PWD and  HOME  we can   echo    PWD   HOME          EDIT  Thanks for Mark Haferkamp in the comments for the note on quoting escaping      Note how the variable  HOME contains slashes but this didn t break anything   Further reading  Advanced Bash-Scripting Guide  If using sed is a must  be sure to escape every character

[bash] Replace one substring for another string in shell script

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