Bash – How to rename multiple files by replacing word in file name geting from the shell script variables

I don't understand what particular problem you are stuck on. Your description is really unclear. So I'll give some general advice on simplifying the script; if it's not enough to solve your problem, try to come up with a clearer explanation.

I'm pretty sure this script is much more complicated than it needs to be. Spending a few minutes browsing the documentation of a command to see if one of its options could help you can save hours of debugging. Spending a few minutes thinking about the general structure of the script can save hours of debugging.

Here are several ways in which you could have made your script simpler.

• All variable substitutions should be inside double quotes, i.e., always write "$foo" and not just $foo. You've done it sometimes, but not systematically. Always use double quotes unless you know why you do not want them in a particular case.

• Here's a simpler way of writing your help function; it's called a “here document”.

  function help()
  {
      cat <<EOF
  This script is responsible for simply recursively searching patterns
  given in [INPUT FILE] in [PATH]. If pattern is not found then it is
  written to [OPTIONAL OUTPUT FILE]. If [OPTIONAL OUTPUT FILE] is not
  given the default [OUTPUT FILE] name is: out
  Usage: $0 [INPUT FILE] [PATH TO DIRECTORY] [OPTIONAL OUTPUT FILE]
  e.g. : $0 input_file /var/www/html/ output_file
  or   : $0 help -> this help
  EOF
  }
  

• Give your script a non-zero exit code to indicate failure:

  if [ $# -lt 2 ]; then help; exit 2; fi
  if [ ! -e "$in" ]; then echo "Input file: $1 does not exist"; exit 2; fi
  if [ ! -d "$path" ]; then  echo "Path: $path does not exist"; exit 2; fi
  

• Modifying the input file in is surprising, and you can combine the whitespace-only line removal with the multiple sed expressions that add a backslash before some characters.

  <"$in" sed -e '/^ *$/d' -e 's,[-\\".],\\&,g' > "$tmp"
  

  However the quoting you perform here is strange. Why are you quoting - and ", which are not special to grep, but not * and [ which are special? What is the syntax of the patterns supposed to be?

  If you meant the patterns to be literal strings to look for, all this work is unnecessary (except for removing whitespace-only lines): call grep -F.

• In the part that reads the lines from $tmp, you don't need the counter variable, you can just append to the array. You also need to pass the -r argument to the read built-in, so that it doesn't strip some backslashes.

  while read -r line; do
      linesTable+=("$line")
  done <"$tmp"
  

• In the loop over the patterns, you store the output of grep in a variable, but all you're doing is testing if grep found a match. It would be a lot easier (and faster) to use the return code of grep for that. (I've also removed what is presumably debugging output from the loop; you don't need tee to append to a file, just use the redirection operator >>.)

  for line in "${linesTable[@]}"; do
      grep -q -r -- "$line" "$path"
      if [ $? -ne 0 ]; then echo "$line" >>"$tmp"; fi
  done
  

• You don't need to free memory at the end of the script. If this was really a function that was part of a bigger script, you should declare them with the local builtin.

Here's a restructured version of the part of your script after the command line parsing. I've incorporated the local changes outlined above and used functions to make the structure clearer. Note that the clearer structure means I don't need to use a temporary file. I don't know if the resulting script does what you want, since you don't explain precisely what you want.

function extract_patterns () {
    <"$in" sed -e '/^ *$/d' -e 's,[-\\".],\\&,g'
}

function report_missing_patterns () {
  local pattern
  for pattern in "$@"; do
    grep -q -r -- "$pattern" "$path"
    if [ $? -ne 0 ]; then printf "%s\n" "$pattern"; fi
  done
}

process_patterns () {
  local patterns line
  patterns=()
  while read -r line; do
      patterns+=("$line")
  done
  report_missing_patterns "${patterns[@]}" | sort -u >"$out"
}

extract_patterns | process_patterns

sed '/enabled=1/a\priority=10' /etc/yum.repos.d/epel.repo

Specify an in-place editing option (-i) if you want (makes the backup with .bak extension first):

sed -i.bak '/enabled=1/a\priority=10' /etc/yum.repos.d/epel.repo

Now i want use sed to do the following 1.Find the FIRST occurrence of worker_processes in that conf and replace text with worker_processes 4;

sed '0,/worker_processes [0-9]*;/s//worker_processes 4;/' /etc/nginx/nginx.conf

One last suggestion I used sed -i 's/enabled=0/enabled=1/g' /etc/yum.repos.d/remi.repo to change enabled=0 to enabled=1 under the [remi] section in remi.repo. However i have a feeling that it may modify all enabled=0 in that file , which will wreak the server.Can anyone suggest a better code

Here for you:

sed '/\[remi\]/,/enabled=0/ { s/enabled=0/enabled=1/ }' remi.repo

Another stuff i am not sure of:P I want to edit a file that has this as Text Testing = "0"(Yes it has quotes and i need to keep it) It should be modified from Testing = "0" to Testing = "1"(with quotes)

sed 's/Testing = "0"/Testing = "1"/g'

Also i need to add some text with quotes at the end of a file with sed Like "Thanks Quanta"(with quote) For php you put a \ with echoing quotes , don't know how it is done for bash

sed '$a"Werulz, you are welcome"\'

Another thing I need to modify a line in a conf but i don't remember what is the whole of text to replaced

Like its listen = something; , i want to modify it to listen = /tmp/php5-fpm.sock;

sed 's/listen = .*/listen = \/tmp\/php5-fpm.sock;/'