How to cat EOF a file containing code

Question

I want to print code into a file using cat  lt  lt EOF  gt  gt    cat  lt  lt EOF  gt  gt  brightup sh   bin bash curr  cat  sys class backlight intel backlight actual brightness  if    curr -lt 4477    then    curr    curr 406       echo  curr   gt   sys class backlight intel backlight brightness  fi EOF   but when I check the file output  I get this     bin bash curr 1634 if    -lt 4477    then    curr 406     echo    gt   sys class backlight intel backlight brightness  fi   I tried putting single quotes but the output also carries the single quotes with it  How can I avoid this issue

User · Accepted Answer

You only need a minimal change  single-quote the here-document delimiter after  lt  lt   cat  lt  lt  EOF   gt  gt  brightup sh  or equivalently backslash-escape it  cat  lt  lt  EOF  gt  gt brightup sh  Without quoting  the here document will undergo variable substitution  backticks will be evaluated  etc  like you discovered  If you need to expand some  but not all  values  you need to individually escape the ones you want to prevent  cat  lt  lt EOF  gt  gt brightup sh    bin sh   Created on   date      lt  lt -- this will be evaluated before cat   echo  quot   HOME will not be evaluated because it is backslash-escaped quot  EOF  will produce    bin sh   Created on Fri Feb 16 11 00 18 UTC 2018 echo  quot  HOME will not be evaluated because it is backslash-escaped quot   As suggested by  fedorqui  here is the relevant section from man bash   Here Documents This type of redirection instructs the shell to read input from the current source until a line containing only delimiter  with no trailing blanks  is seen   All of the lines read up to that point are then used as the standard input for a command  The format of here-documents is         lt  lt  - word               here-document       delimiter  No  parameter  expansion  command substitution  arithmetic expansion  or pathname expansion is performed on word   If any characters in word are quoted  the delimiter is the result of quote removal on word  and the lines in  the  here-document are not expanded   If word is unquoted  all lines of the here-document are subjected to parameter expansion  command substitution  and arithmetic expansion   In the latter case  the character sequence   lt newline gt  is ignored   and    must  be used to quote the characters       and

User · Answer

Or  using your EOF markers  you need to quote the initial marker so expansion won t be done    -----v---v------ cat  lt  lt  EOF   gt  gt  brightup sh    bin bash curr  cat  sys class backlight intel backlight actual brightness  if    curr -lt 4477    then    curr    curr 406       echo  curr   gt   sys class backlight intel backlight brightness  fi EOF   IHTH

User · Answer

This should work  I just tested it out and it worked as expected  no expansion  substitution  or what-have-you took place    cat  lt  lt  lt       bin bash curr  cat  sys class backlight intel backlight actual brightness  if    curr -lt 4477    then   curr    curr 406      echo  curr   gt   sys class backlight intel backlight brightness  fi   gt  file   use overwrite mode so that you don t keep on appending the same script to that file over and over again  unless that s what you want     Using the following also works   cat  lt  lt  lt     gt  file      code        Also  it s worth noting that when using heredocs  such as  lt  lt  EOF  substitution and variable expansion and the like takes place   So doing something like this   cat  lt  lt  EOF  gt  file cd   HOME  echo   PWD    echo the current path EOF   will always result in the expansion of the variables  HOME and  PWD   So if your home directory is  home foobar and the current path is  home foobar bin  file will look like this   cd   home foobar  echo   home foobar bin    instead of the expected   cd   HOME  echo   PWD

User · Answer

I know this is a two year old question  but this is a quick answer for those searching for a  how to   If you don t want to have to put quotes around anything you can simply write a block of text to a file  and escape variables you want to export as text  for instance for use in a script  and not escape one s you want to export as the value of the variable     bin bash  FILE NAME  quot test txt quot  VAR EXAMPLE  quot   quot string  quot  quot   cat  gt    FILE NAME   lt  lt  EOF    VAR EXAMPLE    VAR EXAMPLE  in   FILE NAME    EOF  Will write  quot   VAR EXAMPLE   quot string quot  in test txt quot  into test txt This can also be used to output blocks of text to the console with the same rules by omitting the file name    bin bash  VAR EXAMPLE  quot   quot string  quot  quot   cat  lt  lt  EOF    VAR EXAMPLE    VAR EXAMPLE  to console  EOF  Will output  quot   VAR EXAMPLE   quot string quot  to console quot  to the console

[linux] How to cat <<EOF >> a file containing code?

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