Implementation of shell script replacement function

Shell It's a use. C A program written in a language , It is used by users Linux The bridge .Shell It's a command language , Another programming language . Shell It's an application , This application provides an interface , Users access the services of the operating system kernel through this interface .

Shell Script （shell script）, It's for shell Write the script . function Shell There are two ways to script ： 1、 As an executable Save the code as test.sh, and cd Go to the appropriate directory ： chmod +x ./test.sh # Give the script permission to execute ./test.sh # Execute the script

2、 As interpreter parameters The way it works is , Run the interpreter directly , The parameter is shell The filename of the script , Such as ： /bin/bash test.sh

Purpose ： take jvm The setting at startup is 2048M The memory allocation of is adjusted to 1024M

#!/bin/bash  # Indicates that the shell The path to the script interpreter

baseDir="/home/q/www"  # Defines a directory variable

function replace() { # Defines a method , In the following for  Cyclic invocation

  filename=$1  # Receive the first parameter

  from=$2 # Receive the second parameter

  to=$3 # Receive the third parameter

  echo 'Processing '$filename  # Output the file name being processed

  sudo sed -i "s/$from/$to/g" $filename  # Real replacement command sed

  c=`grep "$from" $filename | wc -l` # Count the number of times after replacement

  if [[ $c != 0 ]]; then  # If the number of times after statistics is not 0 It means that the replacement fails

    echo "replace $filename failed!"  # Output the prompt of replacement failure

    exit 1 # sign out

  fi #if The end of judgment

  echo "Replace $filename success!"  # Output the prompt of successful replacement

}

for this in `find $baseDir -type f -name startenv.sh`;   # Find the file named startenv.sh  The file of , And implement for  loop

do # Start execution

    #  Replace jdk To configure

    echo $this  # Output the found file name and full path

    replace $this "2048" "1024" # Call the method defined above to perform the replacement operation

done # End to perform