Linux
 
sed -in-place -e 's/old/new/g' text.txt
 
 
Windows
 
@echo off        
    
if %1%.==. (        
    echo Usage: %0% FILE_FULL_PATH SOURCE_STRING DESTINATION_STRING        
    echo Where: FILE_FULL_PATH is the full path of the file to be replaced in        
    echo                SOURCE_STRING is string to be replaced        
    echo                DESTINATION_STRING is string to be replaced as        
    pause        
    exit        
)        
    
if %2%.==. (        
    echo Usage: %0% FILE_FULL_PATH SOURCE_STRING DESTINATION_STRING        
    echo Where: FILE_FULL_PATH is the full path of the file to be replaced in        
    echo                SOURCE_STRING is string to be replaced        
    echo                DESTINATION_STRING is string to be replaced as        
    pause        
    exit        
)        
    
if %3%.==. (        
    echo Usage: %0% FILE_FULL_PATH SOURCE_STRING DESTINATION_STRING        
    echo Where: FILE_FULL_PATH is the full path of the file to be replaced in        
    echo                SOURCE_STRING is string to be replaced        
    echo                DESTINATION_STRING is string to be replaced as        
    pause        
    exit        
)        
    
setlocal enabledelayedexpansion        
    
set file=        
rem set /p replaced= Please input the file full path：        
set "file=%1%"    
for %%i in ("%file%") do set file=%%~fi        
echo.        
    
set replaced=        
rem set /p replaced= Source String：        
set "replaced=%2%"            
echo.        
    
set all=        
rem set /p all= Destination String：        
set "all=%3%"    
echo.        
    
for /f "delims=" %%i in ('type "%file%"') do (        
    set str=%%i        
    set "str=!str:%replaced%=%all%!"        
    echo !str!>>"%file%".tmp        
)        
    
copy "%file%" "%file%".bak >nul 2>nul        
move "%file%".tmp "%file%"        
rem start "" "%file%"