Add ability to print process_env environment

1 files changed, 24 insertions, 0 deletions

diff --git a/libbutl/process-io.mxx b/libbutl/process-io.mxx
index 5471846..d07a212 100644
--- a/libbutl/process-io.mxx
+++ b/libbutl/process-io.mxx
@@ -40,4 +40,28 @@ LIBBUTL_MODEXPORT namespace butl
     process::print (o, a.argv, a.argc);
     return o;
   }
+
+  // Print the environment variables and the current working directory (if
+  // specified) in a POSIX shell command line notation. The process path
+  // itself is not printed. For example:
+  //
+  // LC_ALL=C
+  //
+  // If an environment variable is in the `name` rather than in the
+  // `name=value` form, then it is considered unset. Since there is no POSIX
+  // way to unset a variable on the command line, this information is printed
+  // as `name=` (ambiguous with assigning an empty value but the two cases are
+  // normally handled in the same way). For example:
+  //
+  // PATH= LC_ALL=C
+  //
+  // Note that since there is no POSIX way to change the current working
+  // directory of a command to be executed, this information is printed in a
+  // pseudo-notation by assigning to PWD (which, according POSIX, would result
+  // in the undefined behavior of the cwd utility). For example:
+  //
+  // PWD=/tmp LC_ALL=C
+  //
+  LIBBUTL_SYMEXPORT std::ostream&
+  operator<< (std::ostream&, const process_env&);
 }