Introduction

       The  unix:  module provides access to features that only make sense on UNIX-like operating
       systems, such as Linux, FreeBSD, and macOS.

       On non-UNIX operating systems, such as MS Windows, this namespace does not exist  and  use
       unix  will  fail.   Use  the  $platform:is-unix variable to determine if this namespace is
       usable.

Variables

   $unix:umask {#unix:umask}
       The file mode creation mask.  Its value is a string in Elvish octal  representation;  e.g.
       0o027.  This makes it possible to use it in any context that expects a $number.

       When  assigning  a  new  value a string is implicitly treated as an octal number.  If that
       fails the usual rules for interpreting numbers are used.  The  following  are  equivalent:
       unix:umask  =  027  and  unix:umask = 0o27.  You can also assign to it a float64 data type
       that has no fractional component.  The assigned value must be  within  the  range  [0  ...
       0o777], otherwise the assignment will throw an exception.

       You  can  do  a  temporary  assignment  to  affect a single command; e.g.  umask=077 touch
       a_file.  After the command completes the old umask will be restored.  Warning:  Since  the
       umask  applies  to  the entire process, not individual threads, changing it temporarily in
       this manner is dangerous if you are doing anything in parallel.  Such  as  via  the  peach
       command.