how to set environment variable from file contents?

Question

On windows/cygwin, i want to be able save the PATH variable to file on one machine and load it onto the other machine;

for storing the variable i am doing:

echo %PATH% > dat

however, not sure how to load it later.

set PATH=???????

Thanks Rami

Just use: `set /P PATH=< dat` – Aacini Jan 07 '12 at 03:28 — Aacini, Jan 07 '12 at 03:28
post your comment as answer and I'd vote it up. – PA. Jan 08 '12 at 15:10 — PA., Jan 08 '12 at 15:10

score 16 · Answer 1 · answered Jan 11 '12 at 04:48

16

Just use: set /P PATH=< dat

You must note that echo %PATH% > dat insert an additional space after %PATH% value; that space may cause problems if an additional path is later added to PATH variable. Just eliminate the extra space this way: echo %PATH%> dat.

answered Jan 11 '12 at 04:48

Aacini

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1

For me this only works for the first 1024 characters of the file. Sorry, I missed the fact this was on cygwin. Maybe it works better under cygwin. – Russell Gallop Apr 24 '14 at 10:15
@RussellGallop, did you find a workaround for this limitation? – xverges May 28 '14 at 12:08
`set /P` can only read 1024 characters. To read more, use `for /F` as shown in SpaceMonkey answer below. – Aacini May 28 '14 at 15:41

score 5 · Answer 2 · answered Jan 07 '12 at 14:55

echo %PATH% will fail if the PATH contains an unquoted & or ^ (this is not likely, but certainly possible)

A more reliable solution is to use:

setlocal enableDelayedExpansion
echo !path!>dat

Then you can use Aacini's suggested method of reading the value back in

set /p "PATH=" <dat

score 4 · Answer 3 · answered Mar 27 '13 at 16:08

4

This might be evil but on Windows I am using this:

for /F %%g in (dat) do set PATH=%%g

and this to write the file because I had trouble with spaces

echo>dat %PATH%

answered Mar 27 '13 at 16:08

SpacedMonkey

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You must use the "delims" option if you want to manage spaces: for /F "delims=" %%g in (dat) – efdummy Jun 09 '21 at 20:05

ziesemer · Answer 4 · 2012-01-07T03:20:46.610

3

Being dependent upon Cygwin, how how about putting the command in your saved file, e.g.:

echo "export PATH=$PATH" > dat

Then sourcing the script later to set the path:

. ./dat

Note that "sourcing" the script (vs. just executing it) is required for it to modify your current environment - and not just new child environments.

edited Jan 07 '12 at 03:20

answered Jan 07 '12 at 03:13

ziesemer

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on windows i had finally to do ' echo set PATH=%PATH% > dat.bat '; thanks – sramij Jan 07 '12 at 03:44

score 0 · Answer 5 · answered Jun 09 '21 at 20:12

The following sample works even with spaces and dot in the path value:

@REM Backup PATH variable value in a file
@REM Set PATHBACKUP variable with value in the file

@echo %PATH% > pathvalue.txt
@type pathvalue.txt
@for /f "delims=" %%l in (pathvalue.txt) do (
  @set line=%%l
)
@set PATHBACKUP=%line%
@echo %PATHBACKUP%

how to set environment variable from file contents?

5 Answers5