PowerShell tee-Object generates empty lines in output, when used in db2 commands - powershell

Question

When I use powershell tee-object cmdlet to save the output to a file, blank lines are created between each actual line. Output gets doubled and ugly, in both screen output, as well in the redirected file.
regular command, and output:
# db2 connect to sample
Database Connection Information
Database server = DB2/NT64 11.5.0.0
SQL authorization ID = SAMUEL
Local database alias = SAMPLE
but, when you use Tee-Object against it... here is what happens:
# db2 connect to sample | Tee-Object test.out
Database Connection Information
Database server = DB2/NT64 11.5.0.0
SQL authorization ID = SAMUEL
Local database alias = SAMPLE
In both screen output, and also in the generated file a well:
# type test.out
Database Connection Information
Database server = DB2/NT64 11.5.0.0
SQL authorization ID = SAMUEL
Local database alias = SAMPLE
--- edit ---
#js2010, here is the entire hex-format for better reading.. cant paste it properly in the comments.
# format-hex test.out
Path: E:\PowerShell_Tests\db2mon\test.out
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00000000 FF FE 0D 00 0A 00 0D 00 0A 00 20 00 20 00 20 00 .þ........ . . .
00000010 44 00 61 00 74 00 61 00 62 00 61 00 73 00 65 00 D.a.t.a.b.a.s.e.
00000020 20 00 43 00 6F 00 6E 00 6E 00 65 00 63 00 74 00 .C.o.n.n.e.c.t.
00000030 69 00 6F 00 6E 00 20 00 49 00 6E 00 66 00 6F 00 i.o.n. .I.n.f.o.
00000040 72 00 6D 00 61 00 74 00 69 00 6F 00 6E 00 0D 00 r.m.a.t.i.o.n...
00000050 0A 00 0D 00 0A 00 0D 00 0A 00 0D 00 0A 00 20 00 .............. .
00000060 44 00 61 00 74 00 61 00 62 00 61 00 73 00 65 00 D.a.t.a.b.a.s.e.
00000070 20 00 73 00 65 00 72 00 76 00 65 00 72 00 20 00 .s.e.r.v.e.r. .
00000080 20 00 20 00 20 00 20 00 20 00 20 00 20 00 3D 00 . . . . . . .=.
00000090 20 00 44 00 42 00 32 00 2F 00 4E 00 54 00 36 00 .D.B.2./.N.T.6.
000000A0 34 00 20 00 31 00 31 00 2E 00 35 00 2E 00 30 00 4. .1.1...5...0.
000000B0 2E 00 30 00 0D 00 0A 00 0D 00 0A 00 20 00 53 00 ..0......... .S.
000000C0 51 00 4C 00 20 00 61 00 75 00 74 00 68 00 6F 00 Q.L. .a.u.t.h.o.
000000D0 72 00 69 00 7A 00 61 00 74 00 69 00 6F 00 6E 00 r.i.z.a.t.i.o.n.
000000E0 20 00 49 00 44 00 20 00 20 00 20 00 3D 00 20 00 .I.D. . . .=. .
000000F0 53 00 41 00 4D 00 55 00 45 00 4C 00 0D 00 0A 00 S.A.M.U.E.L.....
00000100 0D 00 0A 00 20 00 4C 00 6F 00 63 00 61 00 6C 00 .... .L.o.c.a.l.
00000110 20 00 64 00 61 00 74 00 61 00 62 00 61 00 73 00 .d.a.t.a.b.a.s.
00000120 65 00 20 00 61 00 6C 00 69 00 61 00 73 00 20 00 e. .a.l.i.a.s. .
00000130 20 00 20 00 3D 00 20 00 53 00 41 00 4D 00 50 00 . .=. .S.A.M.P.
00000140 4C 00 45 00 0D 00 0A 00 0D 00 0A 00 0D 00 0A 00 L.E.............
00000150 0D 00 0A 00 ....
Also, your 2nd test reveals that the problem is not about using tee-object cmdlet, but actually, just piping the output causes it...
Another information, If I perform a redirect to a file, from a regular windows cmd window, the issue does not happens,
from cmd window:
E:\PowerShell_Tests\db2mon>db2 connect to sample > cmd.out
E:\PowerShell_Tests\db2mon>type cmd.out
Database Connection Information
Database server = DB2/NT64 11.5.0.0
SQL authorization ID = SAMUEL
Local database alias = SAMPLE
but, performing the same redirect from a powershell session, created the double lines again:
# db2 connect to sample > pwsh.out
PS [Samuel]E:\PowerShell_Tests\db2mon
# Get-Content pwsh.out
Database Connection Information
Database server = DB2/NT64 11.5.0.0
SQL authorization ID = SAMUEL
Local database alias = SAMPLE
--- end edit ---
--- edit 2 ---
#js2010
# db2 connect to sample | format-hex
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00000000 20 20 20 44 61 74 61 62 61 73 65 20 43 6F 6E 6E Database Conn
00000010 65 63 74 69 6F 6E 20 49 6E 66 6F 72 6D 61 74 69 ection Informati
00000020 6F 6E on
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00000000 20 44 61 74 61 62 61 73 65 20 73 65 72 76 65 72 Database server
00000010 20 20 20 20 20 20 20 20 3D 20 44 42 32 2F 4E 54 = DB2/NT
00000020 36 34 20 31 31 2E 35 2E 30 2E 30 64 11.5.0.0
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00000000 20 53 51 4C 20 61 75 74 68 6F 72 69 7A 61 74 69 SQL authorizati
00000010 6F 6E 20 49 44 20 20 20 3D 20 53 41 4D 55 45 4C on ID = SAMUEL
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00000000 20 4C 6F 63 61 6C 20 64 61 74 61 62 61 73 65 20 Local database
00000010 61 6C 69 61 73 20 20 20 3D 20 53 41 4D 50 4C 45 alias = SAMPLE
--- end edit 2 ---
Does any one has any clue on what is going on, and how can I "fix" it ?
Thanks

Answer 1

As your Format-Hex output implies, db2 - bizarrely - uses CRCRLF ("`r`r`n" in PowerShell terms) rather than the usual CRLF sequences ("`r`n") as newlines (to separate its output lines) - it is a behavior it shares with sfc.exe.
When you print to the display, this anomaly doesn't surface, but it does when you capture or redirect the output, such as via Tee-Object.
The workaround is to eliminate every other line, which discards the extra lines that result from PowerShell interpreting a CR ("`r") by itself as a newline too:
$i = 0
db2 ... | Where-Object { ++$i % 2 } | Tee-Object test.out
Update: You've since provided a convenient wrapper function based on this solution in your own answer.

Answer 2

for other Db2 DBAs out there trying to use powershell as me..
I have created this small hack, to handle this for all my db2 ps sessions.
Edit your powershell user profile, creating an function and alias as above:
$Home[My ]Documents\PowerShell\Microsoft.PowerShell_profile.ps1 :
# db2 settings for powershell
Set-Item -Path env:DB2CLP -value "**$$**"
# Handle db2 output, avoiding doubled lines due 'CRCRLF' pattern
Function Handle-Db2 {
$i = 0
db2 $args | Where-Object { ++$i % 2 }
}
New-Alias -Name "db2ps" Handle-Db2
Now, if you want to use the hacked version, instead of calling db2 .... you can use db2ps ... instead and have a proper output.
# db2ps describe table employee | Tee-Object employee.out
Data type Column
Column name schema Data type name Length Scale Nulls
------------------------------- --------- ------------------- ---------- ----- ------
EMPNO SYSIBM CHARACTER 6 0 No
FIRSTNME SYSIBM VARCHAR 12 0 No
MIDINIT SYSIBM CHARACTER 1 0 Yes
LASTNAME SYSIBM VARCHAR 15 0 No
WORKDEPT SYSIBM CHARACTER 3 0 Yes
PHONENO SYSIBM CHARACTER 4 0 Yes
HIREDATE SYSIBM DATE 4 0 Yes
JOB SYSIBM CHARACTER 8 0 Yes
EDLEVEL SYSIBM SMALLINT 2 0 No
SEX SYSIBM CHARACTER 1 0 Yes
BIRTHDATE SYSIBM DATE 4 0 Yes
SALARY SYSIBM DECIMAL 9 2 Yes
BONUS SYSIBM DECIMAL 9 2 Yes
COMM SYSIBM DECIMAL 9 2 Yes
14 record(s) selected.
# db2ps describe table employee | Select-String "DEC"
SALARY SYSIBM DECIMAL 9 2 Yes
BONUS SYSIBM DECIMAL 9 2 Yes
COMM SYSIBM DECIMAL 9 2 Yes
It would be nice if IBM fix this odd CRCRLF behavior on db2 commands on windows.
Until this not happens, enjoy!
Regards