How to remove trailing whitespaces with sed

Question

I have a simple shell script that removes trailing whitespace from a file  Is there any way to make this script more compact  without creating a temporary file    sed  s    t        1  gt   1   tmp cat  1   tmp  gt   1 rm  1   tmp

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I have a script in my  bashrc that works under OSX and Linux  bash only     function trim trailing space       if       -eq 0     then     echo   FUNCNAME will trim  in place  trailing spaces in the given file  remove unwanted spaces at end of lines       echo  Usage        echo   FUNCNAME file      return   fi   local file  1   unamestr   uname    if     unamestr     Darwin      then      specific case for Mac OSX     sed -E -i      s    space          file   else     sed -i   s    space          file   fi     to which I add   SRC FILES EXTENSIONS  js ts cpp c h hpp php py sh cs sql json ini xml conf   function find source files       if       -eq 0     then     echo   FUNCNAME will list sources files  having extensions  SRC FILES EXTENSIONS       echo  Usage        echo   FUNCNAME folder      return   fi   local folder  1    unamestr   uname    if     unamestr     Darwin      then      specific case for Mac OSX     find -E  folder -iregex         SRC FILES EXTENSIONS      else      Rhahhh  lovely     local extensions escaped   echo  SRC FILES EXTENSIONS   sed s           g       echo  extensions escaped  extensions escaped      find  folder -iregex          extensions escaped        fi    function trim trailing space all source files       for f in   find source files     do trim trailing space  f done

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In the specific case of sed  the -i option that others have already mentioned  is far and away the simplest and sanest one   In the more general case  sponge  from the moreutils collection  does exactly what you want  it lets you replace a file with the result of processing it  in a way specifically designed to keep the processing step from tripping over itself by overwriting the very file it s working on  To quote the sponge man page      sponge reads standard input and writes it out to the specified file  Unlike a shell redirect  sponge soaks up all its input before writing the output file  This allows constructing pipelines that read from and write to the same file    https   joeyh name code moreutils

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Just for fun      bin bash  FILE  1  if    -z  FILE     then    echo  You must pass a filename -- exiting   gt  amp 2    exit 1 fi  if      -f  FILE     then    echo  There is not file   FILE  here -- exiting   gt  amp 2    exit 1 fi  BEFORE  wc -c   FILE    cut --delimiter     --fields 1      gt  gt  gt  gt  gt  gt  gt  gt  gt  gt  sed -i bak -e s    t         FILE     lt  lt  lt  lt  lt  lt  lt  lt  lt  lt   AFTER  wc -c   FILE    cut --delimiter     --fields 1   if          0     then    echo  Some error occurred   gt  amp 2 else    echo  Filtered   FILE  from  BEFORE characters to  AFTER characters  fi

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Thanks to codaddict for suggesting the -i option   The following command solves the problem on Snow Leopard  sed -i    -e s    t         1

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To only strip whitespaces  in my case spaces and tabs  from lines with at least one non-whitespace character  this way empty indented lines are not touched    sed -i -r  s      t      t     1     file

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At least on Mountain Lion  Viktor s answer will also remove the character  t  when it is at the end of a line  The following fixes that issue   sed -i    -e s    space           1

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You can use the in place option -i of sed for Linux and Unix   sed -i  s    t         1    Be aware the expression will delete trailing t s on OSX  you can use gsed to avoid this problem   It may delete them on BSD too   If you don t have gsed  here is the correct  but hard-to-read  sed syntax on OSX   sed -i    -E  s       t           1    Three single-quoted strings ultimately become concatenated into a single argument expression  There is no concatenation operator in bash  you just place strings one after the other with no space in between   The    t  resolves as a literal tab-character in bash  using ANSI-C quoting   so the tab is correctly concatenated into the expression

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For those who look for efficiency  many files to process  or huge files   using the   repetition operator instead of   makes the command more than twice faster   With GNU sed   sed -Ei  s    t         1  sed -i  s    t          1      The same without extended regex   I also quickly benchmarked something else  using    t  instead of    space    also significantly speeds up the process  GNU sed v4 4    sed -Ei  s    t         1   real    0m0 335s user    0m0 133s sys 0m0 193s  sed -Ei  s    space           1   real    0m0 838s user    0m0 630s sys 0m0 207s  sed -Ei  s    t         1   real    0m0 882s user    0m0 657s sys 0m0 227s  sed -Ei  s    space           1   real    0m1 711s user    0m1 423s sys 0m0 283s

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var1   t t Test String trimming     echo  var1 Var2   echo    var1     sed  s     space       s    space          echo  Var2

User · Answer

It is best to also quote  1   sed -i bak  s    blank           1

[sed] How to remove trailing whitespaces with sed?

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