Batch windows - read file and modify line

Question

I want to automate some actions with a batch script, one thing I have to do, is to replace a date on a file, with the current date. I tried to do something, dut it's like the line of my file is empty...

SET planningFile=<My file with full path>

set mydate=%date:~6,4%%date:~3,2%%date:~0,2%

FOR /F %%i IN ('TYPE "%planningFile%"') DO (
    SET str=%%i
    SET str=%str:~8,%
    ECHO %mydate%%srt% > "%planningFile%~"
)
DEL "%planningFile%"
RENAME "%planningFile%~" "%planningFile%"

a line of that file looks like 20140513;54;aaaa:54 (CSV file). Anyone could help me ?

Answer 1

Within a block statement (a parenthesised series of statements), the entire block is parsed and then executed. Any %var% within the block will be replaced by that variable's value at the time the block is parsed - before the block is executed - the same thing applies to a FOR ... DO (block).

Hence, IF (something) else (somethingelse) will be executed using the values of %variables% at the time the IF is encountered.

Two common ways to overcome this are 1) to use setlocal enabledelayedexpansion and use !var! in place of %var% to access the changed value of var or 2) to call a subroutine to perform further processing using the changed values.

Hence

SETLOCAL ENABLEDELAYEDEXPANSION
FOR /F %%i IN ('TYPE "%planningFile%"') DO (
    SET "str=%%i"
    SET "str=!str:~8!"
    ECHO %mydate%!sTR! > "%planningFile%~"
)

Note : - your line has `ECHO ...%srt% ....

The > should be >> if you wish to append rather than create the file anew.

See any number of SO articles on delayedexpansion for hundreds of examples.