Topic       : TOS - The Operating System
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View Ref-File8.18.1  shel_envrn                                                 TOS

 Name:         »Shell environment« - Obtains value of environmental 
               variables.

 Opcode:       125

 Syntax:       int16_t shel_envrn ( int8_t **sh_epvalue, int8_t 
               *sh_eparm );

 Description:  The call shel_envrn searches the current environment 
               string to find the value of a specific environmental 
               variable of the AES. The following apply:

                Parameter   Meaning

                sh_epvalue  Name of the environmental variable
                sh_eparm    After the call contains the value of the 
                            corresponding variable

               Example: If the current environment is, say: 
               'PATH=C:\;D:\;E:\' then calling shel_envrn with 
               sh_eparm pointing to the string 'PATH=' would set the 
               pointer pointed to by sh_epvalue to the start of the 
               string 'C:\;D:\;E:\'. Note that the character string 
               pointed to by sh_eparm should include the name of the 
               variable and the 'equals' sign.

               Note: To change the AES environment, one should hook 
               into the exec_os vector, which is also used to launch 
               GEM. In the called routine, the basepage pointer lies 
               on the stack (as in a program). In this basepage one 
               can then simply enter a pointer to the new environment.

               But a word of warning: In AES versions lower than 1.4, 
               only the first 50 bytes will be adopted; also these 
               only accept semicolons as separators between multiple 
               'PATH=' arguments, while later versions accept commas 
               as well.

               Another tip: If the pointer returned for 'PATH=' points 
               to a NULLbyte, one should increase it by the value 1 to 
               get the correct result.

 Return value: The function always returns a value of 1.

 Availability: All AES versions.

 Group:        Shell library

 See Also:     Binding