SETENVIRON

[jdmcbride]

in Linux, I can set an environment variable with:

SETENVIRON("COUNT=123")
print ENVIRON("COUNT") will return 123 as a string

so far so good....

Doing this fails:

MYCOUNT="123"

SETENVIRON("COUNT=" + MYCOUNT)
print ENVIRON("COUNT") will return a NULL

Why is that?

[grindstone]

In Windows it works.

[Landeel]

This works:

Code: Select all

dim as string MYCOUNT="COUNT=123"
SETENVIRON(MYCOUNT)
print ENVIRON("COUNT")

This fails:

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dim as string MYCOUNT="123"
SETENVIRON("COUNT=" + MYCOUNT)
print ENVIRON("COUNT") 'will return a NULL

Looks like a bug to me.

[fxm]

It works with Windows.

It can't hurt to try this too:

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dim as string MYCOUNT="123"
SETENVIRON("COUNT=" & MYCOUNT)
print ENVIRON("COUNT") 'will return a NULL

[Landeel]

Code: Select all

dim as string MYCOUNT="123"
SETENVIRON("COUNT=" & MYCOUNT)
print ENVIRON("COUNT") 'will return a NULL

Fails too!

[fxm]

and this?

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dim as string MYCOUNT="123"
SETENVIRON(("COUNT=" + MYCOUNT))
print ENVIRON("COUNT") 'will return a NULL

[badidea]

and this?

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dim as string MYCOUNT="123"
SETENVIRON(("COUNT=" + MYCOUNT))
print ENVIRON("COUNT") 'will return a NULL

Fail

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dim as string MYCOUNT=""
SETENVIRON("COUNT=123" & MYCOUNT)
print ENVIRON("COUNT")

Fail

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dim as string MYCOUNT=""
SETENVIRON(MYCOUNT & "COUNT=123")
print ENVIRON("COUNT")

Fail

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SETENVIRON("COUNT=123" & "")
print ENVIRON("COUNT")

Pass

FreeBASIC Compiler - Version 1.07.1 (2019-09-27), built for linux-x86 (32bit)
and
FreeBASIC Compiler - Version 1.07.1 (2019-09-27), built for linux-x86_64 (64bit)

[fxm]

Look at SetEnviron troubles

When using 'SETENVIRON(envStr)' with Linux, the 'envStr' string must be permanent (a literal, a variable declared in the main code or a static variable declared in a procedure), because Linux does not memorize the string but only a pointer to its data characters.

Short example:

Code: Select all

dim as string MYCOUNT="123"
dim shared as string envStr1
envStr1 = "COUNT=" + MYCOUNT  '' envStr1 must always exist without ever being modified
SETENVIRON(envStr1)
print ENVIRON("COUNT")

If it works, I would add a note (inside paragraph "Platform Differences") in the documentation.

[badidea]

Ah, that make sense.

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sub set()
	dim as string MYCOUNT="123"
	dim as string envStr1
	envStr1 = "COUNT=" + MYCOUNT  '' envStr1 must always exist without ever being modified
	SETENVIRON(envStr1)
end sub

set()
print ENVIRON("COUNT")

Fail

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dim shared as string envStr1

sub set()
	dim as string MYCOUNT="123"
	envStr1 = "COUNT=" + MYCOUNT  '' envStr1 must always exist without ever being modified
	SETENVIRON(envStr1)
end sub

set()
print ENVIRON("COUNT")

Pass

[hhr]

Code: Select all

Setenviron("COUNT=123")
Print Environ("COUNT")

Const As String MYCOUNT1="456"
Setenviron("COUNT=" + MYCOUNT1)
Print Environ("COUNT")

Dim As String MYCOUNT2="789"
Dim As String envStr="COUNT=" + MYCOUNT2
Setenviron(envStr)
Print Environ("COUNT")

Sleep

[fxm]

'Dim As String envStr' works only when this declaration is done in the main code.

[fxm]

If it works, I would add a note (inside paragraph "Platform Differences") in the documentation.

Done:
KeyPgSetenviron → fxm [In Linux, 'SetEnviron' memorizes a pointer to the string data characters and not the string itself]

[hhr]

I don't understand 'never be modified':

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Dim As String MYCOUNT,envStr

MYCOUNT="123"
envStr="COUNT=" + MYCOUNT
Setenviron(envStr)
Print Environ("COUNT")

MYCOUNT="ABCDEF"
envStr="COUNT=" + MYCOUNT
Setenviron(envStr)
Print Environ("COUNT")

Sleep

[fxm]

Try this in Linux (I do not have Linux):

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Dim As String MYCOUNT,envStr

MYCOUNT="123"
envStr="COUNT=" + MYCOUNT
Setenviron(envStr)
Print Environ("COUNT")

envStr="modified"
Print Environ("COUNT")

Sleep

I now think that the denomination of "permanent" is sufficient, given the following explanation about memorizing a pointer only?

[hhr]

Thank you. Output in Linux:

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123       Len=3
          Len=0