File content into unix variable with newlines

Question

I have a text file test txt with the following content   text1 text2    And I want to assign the content of the file to a UNIX variable  but when I do this    testvar   cat test txt  echo  testvar   the result is    text1 text2   instead of  text1 text2    Can someone suggest me a solution for this

User · Answer

Bash -ge 4 has the mapfile builtin to read lines from the standard input into an array variable.

help mapfile 

mapfile < file.txt lines
printf "%s" "${lines[@]}"

mapfile -t < file.txt lines    # strip trailing newlines
printf "%s\n" "${lines[@]}"

See also:

http://bash-hackers.org/wiki/doku.php/commands/builtin/mapfile

User · Answer

This is due to IFS  Internal Field Separator  variable which contains newline      cat xx1 1 2    A  cat xx1    echo  A 1 2    echo    IFS                A workaround is to reset IFS to not contain the newline  temporarily     IFSBAK  IFS   IFS       A  cat xx1    Can use     as well   echo  A 1 2   IFS  IFSBAK   To REVERT this horrible change for IFS   IFS  IFSBAK

User · Answer

Your variable is set correctly by testvar   cat test txt   To display this variable which consist new line characters  simply add double quotes  e g   echo   testvar     Here is the full example     printf  test1 ntest2   gt  test txt   testvar    lt test txt    grep testvar  lt  set  testvar   test1 ntest2    echo   testvar  text1 text2   printf   b    testvar  text1 text2

User · Answer

Just if someone is interested in another option   content     cat test txt     a 0 while    a -le    content       do         echo   content  a           a   a 1  done

User · Answer

The assignment does not remove the newline characters  it s actually the echo doing this  You need simply put quotes around the string to maintain those newlines  echo  quot  testvar quot   This will give the result you want  See the following transcript for a demo  pax gt  cat num1 txt   x   cat num1 txt  line 1 line 2  pax gt  echo  x   echo         echo  quot  x quot  line 1 line 2     line 1 line 2   The reason why newlines are replaced with spaces is not entirely to do with the echo command  rather it s a combination of things  When given a command line  bash splits it into words according to the documentation for the IFS variable   IFS  The Internal Field Separator that is used for word splitting after expansion     the default value is  lt space gt  lt tab gt  lt newline gt    That specifies that  by default  any of those three characters can be used to split your command into individual words  After that  the word separators are gone  all you have left is a list of words  Combine that with the echo documentation  a bash internal command   and you ll see why the spaces are output   echo  -neE   arg       Output the args  separated by spaces  followed by a newline   When you use echo  quot  x quot   it forces the entire x variable to be a single word according to bash  hence it s not split  You can see that with  pax gt  function count       gt     echo        gt    pax gt  count 1 2 3 3 pax gt  count a b c d 4 pax gt  count  x 4 pax gt  count  quot  x quot  1  Here  the count function simply prints out the number of arguments given  The 1 2 3 and a b c d variants show it in action  Then we try it with the two variations on the x variable  The one without quotes shows that there are four words   quot test quot    quot 1 quot    quot test quot  and  quot 2 quot   Adding the quotes makes it one single word  quot test 1 ntest 2 quot

User · Answer

The envdir utility provides an easy way to do this   envdir uses files to represent environment variables  with file names mapping to env var names  and file contents mapping to env var values   If the file contents contain newlines  so will the env var   See https   pypi python org pypi envdir

[bash] File content into unix variable with newlines

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