]
07-23-2023, 10:50 AM
I want to access STDIN from inside a batch file **after** some other commands. I know that the first command in a .BAT file receives STDIN but I want to first run some other commands *and then* capture STDIN. I also want this to work with streamed STDIN i.e. it is not acceptable to capture STDIN to a file at the start with (see workaround below).
Now, I understand that `CON` is the "file" representing STDIN and that `TYPE CON` would output (echo) STDIN. This does not seem to work at all inside a batch file. Indeed, it appears not to represent STDIN but user/host input by keyboard.
**test.bat**
```
TYPE CON > output.txt
```
**Test run:**
```
C:>TYPE myfile.txt | test.bat
```
Expected result: `myfile.txt` is copied into `output.txt`.
Actual result: The batch waits for user input (ignores what is piped to it) and writes user input typed on the keyboard to `output.txt`.
**Workaround**
As a workaround: the following `test.bat` works but does not support streamed input (e.g. from a `tail` command):
```
findstr "^" STDIN.txt
:: I can now run some other commands
:: And finally access my STDIN via STDIN.txt
TYPE STDIN.txt | AWK /e/ > output.txt
```
**UPDATE: Back Story:**
I have a neat CMD which uses powershell to download (via HTTP) an arbitrary .ps1 script (like a package manager would) and execute it on the fly. If I call `REMEXEC.bat mymodule foo bar` it loads and executes `mymodule.ps1` with the parameters `foo` and `bar`.
This works wonderfully for every scenario except piped, streamed input. Using the `findstr "^"` works for piped input but not for an open stream. Using say `AWK /.*/` as the first line of my BAT gets me that streamed input but just pushes the problem down the road.
Ultimately I want a `something.bat` which looks like this (pseudocode):
```
downloadPSModule( "http://myrepo.com/modules/%1.ps1" )
STDIN | executePSModule %2 %3 %4
```
The catch 22 is that `downloadPSModule` happens BEFORE `executePSModule` and thus has no access to STDIN (a privelege reserved for the first line of a BAT).
Now, I understand that `CON` is the "file" representing STDIN and that `TYPE CON` would output (echo) STDIN. This does not seem to work at all inside a batch file. Indeed, it appears not to represent STDIN but user/host input by keyboard.
**test.bat**
```
TYPE CON > output.txt
```
**Test run:**
```
C:>TYPE myfile.txt | test.bat
```
Expected result: `myfile.txt` is copied into `output.txt`.
Actual result: The batch waits for user input (ignores what is piped to it) and writes user input typed on the keyboard to `output.txt`.
**Workaround**
As a workaround: the following `test.bat` works but does not support streamed input (e.g. from a `tail` command):
```
findstr "^" STDIN.txt
:: I can now run some other commands
:: And finally access my STDIN via STDIN.txt
TYPE STDIN.txt | AWK /e/ > output.txt
```
**UPDATE: Back Story:**
I have a neat CMD which uses powershell to download (via HTTP) an arbitrary .ps1 script (like a package manager would) and execute it on the fly. If I call `REMEXEC.bat mymodule foo bar` it loads and executes `mymodule.ps1` with the parameters `foo` and `bar`.
This works wonderfully for every scenario except piped, streamed input. Using the `findstr "^"` works for piped input but not for an open stream. Using say `AWK /.*/` as the first line of my BAT gets me that streamed input but just pushes the problem down the road.
Ultimately I want a `something.bat` which looks like this (pseudocode):
```
downloadPSModule( "http://myrepo.com/modules/%1.ps1" )
STDIN | executePSModule %2 %3 %4
```
The catch 22 is that `downloadPSModule` happens BEFORE `executePSModule` and thus has no access to STDIN (a privelege reserved for the first line of a BAT).
