Ever need to both review some DCL command output on-screen and capture it to a file at the same time?
This happens more often than you might guess. For example, you may need to capture some fast-changing VMS state information (like a process in RWAST state), but doing the same command twice-in-a-row may not show the same overall system state (things can change fast).
Here's how – Use a
tee command file.
$ ! TEE.COM -- split input from SYS$PIPE to SYS$OUTPUT 'F$VERIFY(0)' $ ! and another output (file) $ ! $ ! Usage: @TEE teefile $ ! $ ! Setup: $ TEE == "@com:tee" (in user's LOGIN.COM file) $ ! $ ! Designed for use in VMS pipes, relies on SYS$PIPE as input-stream: $ ! $ ! $ PIPE show system | TEE sys$scratch:capture.lis | search sys$pipe RWAST $ ! ! captures all SHOW SYSTEM output... $ ! or: $ ! $ PIPE show system | search sys$pipe RWAST | TEE sys$scratch:capture.lis $ ! ! captures only SEARCH output matching the requested state... $ ! $ SET NOON $ OPEN /WRITE /ERROR=Oops teefile 'P1' $Loop: $ READ /END_OF_FILE=Done sys$pipe line $ WRITE sys$output line $ WRITE teefile line $ GOTO Loop $Done: $ CLOSE /NOLOG teefile $ EXIT %X01 !'F$VERIFY(0)' $Oops: $ WRITE sys$error "%TEE-E-OPENERR, cannot open ''P1'" $ EXIT %X2C !'F$VERIFY(0)' $ !
This DCL script is designed to work in a DCL
PIPE command construct, the only context where the temporary logical name
SYS$PIPE exists (this is created/deleted by the
PIPE command itself).
The script reads each line (text-data record) from the
SYS$PIPE data-stream (which communicates data from one command to the next command in the pipe chain), and then (re)writes each line out to
SYS$OUTPUT (usually, your terminal screen, but this can be redirected too) and to a file which is named as this script's
Set this up in your own LOGIN.COM file with this command-symbol definition:
$ TEE == "@com:tee"
You can substitute your own subdirectory logical name for the
com logical name shown above.
The two examples in the script show just how easy this is to do – Note however that the placement of the
TEE command-symbol itself in the pipe chain does matter to what is captured into the output file itself.
$ PIPE show system | TEE sys$scratch:capture.lis | search sys$pipe RWAST
…captures all of the SHOW SYSTEM command's output.
$ PIPE show system | search sys$pipe RWAST | TEE sys$scratch:capture.lis
…captures only SEARCH command's output matching the requested state.
Have fun… How many ways or scenarios can you discover where this is useful?