Commenting out a set of lines in a shell script

Question

I was wondering if there is a way to comment out a set of lines in a shell script  How could I do that  We can use       in other programming languages  This is most useful when I am converting using modifying another script  and I want to keep the original lines instead of deleting   It seems a cumbersome job to find and prefix   for all the lines which are not used   Lets say there are 100 lines in the script in consequent lines which are not to used  I want to comment them all out in one go  Is that possible

User · Answer

What if you just wrap your code into function?

So this:

cd ~/documents
mkdir test
echo "useless script" > about.txt

Becomes this:

CommentedOutBlock() {
  cd ~/documents
  mkdir test
  echo "useless script" > about.txt
}

User · Answer

This Perl one-liner comments out lines 1 to 3 of the file orig sh inclusive  where the first line is numbered 0   and writes the commented version to cmt sh   perl -n -e   s 1  e 3           if  i gt   s amp  amp  i lt   e print  i    orig sh  gt  cmt sh   Obviously you can change the boundary numbers as required   If you want to edit the file in place  it s even shorter   perl -in -e   s 1  e 3           if  i gt   s amp  amp  i lt   e print  i    orig sh   Demo    cat orig sh  a b c d e f    perl -n -e   s 1  e 3           if  i gt   s amp  amp  i lt   e print  i    orig sh  gt  cmt sh    cat cmt sh  a  b  c  d e f

User · Answer

Text editors have an amazing feature called search and replace  You don t say what editor you use  but since shell scripts tend to be  nix  and I use VI  here s the command to comment lines 20 to 50 of some shell script    20 50s

User · Answer

if false then     code     fi   false always returns false so this will always skip the code

User · Answer

As per this site      bin bash foo bar     This is a test comment Author foo bar Released under GNU     echo  Init       rest of script

User · Answer

Depending of the editor that you re using there are some shortcuts to comment a block of lines   Another workaround would be to put your code in an  if  0   conditional block

User · Answer

You can use a  here  document with no command to send it to      bin bash echo  Say Something   lt  lt COMMENT1     your comment 1     comment 2     blah COMMENT1 echo  Do something else    Wikipedia Reference

User · Answer

The most versatile and safe method is putting the comment into a void quoted here-document  like this    lt  lt  COMMENT      This long comment text includes   parameter  expansion       command substitution  and    arithmetic     --expansion    COMMENT   Quoting the COMMENT delimiter above is necessary to prevent parameter expansion  command substitution and arithmetic expansion  which would happen otherwise  as Bash manual states and POSIX shell standard specifies   In the case above  not quoting COMMENT would result in variable parameter being assigned text expansion  if it was empty or unset  executing command command substitution  incrementing variable arithmetic and decrementing variable expansion   Comparing other solutions to this   Using if false  then comment text fi requires the comment text to be syntactically correct Bash code whereas natural comments are often not  if only for possible unbalanced apostrophes  The same goes for        comment text   construct   Putting comments into a single-quoted void command argument  as in   comment text   has the drawback of inability to include apostrophes  Double-quoted arguments  as in   comment text   are still subject to parameter expansion  command substitution and arithmetic expansion  the same as unquoted here-document contents and can lead to the side-effects described above   Using scripts and editor facilities to automatically prefix each line in a block with     has some merit  but doesn t exactly answer the question

User · Answer

your code here your code here your code here your code here

User · Answer

You can also put multi-line comments using      comment1comment1 comment2comment2 comment3comment3 comment4comment4    As per the Bash Reference for Bourne Shell builtins     a colon     arguments  Do nothing beyond expanding arguments and performing redirections  The return status is zero   Thanks to Ikram for pointing this out in the post Shell script put multiple line comment

[unix] Commenting out a set of lines in a shell script

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