EnvRun is a small tool written in GO that assists with running processes that need to exchange data via environment variables. By default processes are isolated from each other. Child processes inherit environment variables from their parent processes, but child processes are not allowed to set environment variables on parent processes. Therefore environment variables cannot be passed across processes. EnvRun helps to close this gap by wrapping the execution of processes. EnvRun scans the output (stdout/stderr) of wrapped processes for key expressions that set/reset specific environment variables to pass to other processes executed by EnvRun afterwards. The following key expressions are recognized:
@@envrun[set name='<NAME>' value='<VALUE>']: Sets an environment variable.@@envrun[reset name='<NAME>']: Clears a previously set environment variable.
The next time EnvRun starts a process it explicitly sets these environment variables making them available just as inherited environment variables. If a regularly inherited environment variable and an environment variable set via EnvRun is available, the EnvRun variable takes precedence.
EnvRun is particularly useful on build servers that do not support setting environment variables dynamically (like GoCD). That way tools can publish environment variables for other tools by simply printing to the console. All tools that should take part in the mechanism must be wrapped by EnvRun.
EnvRun is written in GO which makes it highly portable.
Downloads are provided for the following combinations of popular target operating systems and platforms:
linux386amd64armarm64
windows386amd64
If any other target operating system and/or platform is needed and the combination is supported by GO, please open an issue and we'll add support for it.
By default EnvRun puts its database file into the working directory naming it envrun.db. If you need to put the file
somewhere else you can set the ENVRUN_DATABASE environment variable to the appropriate location.
To start a new process you simply have to pass the path of the process and command line arguments to EnvRun:
EnvRun.exe <MyApp.exe> <Args>
The following batch file demonstrates the use of EnvRun. You can see multiple outputs in a line and output to stdout and stderr, afterwards consuming the published environment variables. Please note that these variables are not available outside processes wrapped by EnvRun.
set ENVRUN_DATABASE=.\envrun.db
envrun.exe cmd.exe /C "echo @@envrun[set name='MyVarOnStdout1' value='MyValue1'] @@envrun[set name='MyVarOnStdout2' value='MyValue2']"
envrun.exe cmd.exe /C "echo @@envrun[set name='MyVarOnStderr' value='MyValue3'] 1>&2"
envrun.exe cmd.exe /C "echo MyVar1 = %%MyVarOnStdout1%%, MyVar2 = %%MyVarOnStdout2%%, MyVar3 = %%MyVarOnStderr%%"