What is the difference between !call and call in windows batch - windows

Question

There are 2 files: file1.bat, file2.cmd
file1.bat invokes file2.cmd through command:
db2cmd -i -c -w db2 !call file2 parm1 parm2
This command opens a DB2 command window at the same window and invokes file2.cmd
However, what I can't understand is the function of '!' in front of 'call'.
file2.cmd has below features:
1. DB connection: db2 connect to dbname user username using psw
2. File open: for /F "delims=;" %%i in (input.txt) do (do something)
If passing the incorrect parameters,
---------With 'call' in the file1 command, error shows:
SQL1024N A database connection does not exist. SQLSTATE=08003
---------With '!call' in the file1 command, error shows:
SQL1001N "xxx" is not a valid database name. SQLSTATE=2E000
The system cannot find the file \input.txt.
DB20000I The TERMINATE command completed successfully
So, it looks like 'call' invokes another file and break with high level error message once one of the command fail;
While '!call' invokes another file and continue to run all the commands insides even though there are error, then displays all the error messages of all the failure.
Can someone advise the difference between 'call' and '!call'?

Answer 1

Ok, so simply put, there is no function !call in batch/cmdline. So db2cmd.exe being a commandline processor itself, requires you to use system commands with a preceding !
So though you have a batch file that runs the command with parameters, effectively this is what happens. You are starting db2cmd from this cmd, it then requires you to call another batchfile, but seeing as we are not within the shell of cmd anymore, but rather inside of db2cmd you're then required to tell db2cmd that it is a system command you're executing by doing !call
You can test it by doing on its own db2cmd where you will get to a db2=> prompt and then try and use call vs !call from there.
As for your error message:
SQL1001N "xxx" is not a valid database name. SQLSTATE=2E000
The system cannot find the file \input.txt.
DB20000I The TERMINATE command completed successfully
Try and add a path to the input.txt file
for /F "delims=;" %%i in (C:\somepath\input.txt) do (
something
)
or place input.txt in your working dir.

Answer 2

There is an easier way to handle running Db2 CLP commands inside a Windows batch file.
Db2 on Windows requires that Db2 CLP commands run inside a db2cmd.exe window.
(otherwise a db2 command in a normal cmd.exe window may fail with an error).
The db2cmd.exe is shipped with the Db2 Client for windows.
The solution is to arrange that the script auto-detects whether it is running
inside db2cmd.exe , and if not then run itself under db2cmd.
With this approach the calling script (if there is one)
can simply contain "call file2.bat par1 parm2" and can be executed by the normal CMD.EXE,
while the "file2.bat" can then contain:
#set db2cmd="C:\Program Files\IBM\SQLLIB\BIN\db2cmd.exe"
#if "%DB2CLP%"=="" %db2cmd% /w /c /i "%0" %* && #goto :EOF
#rem If db2cmd.exe is on the system PATH then you can omit the set db2cmd line.
db2 connect to dbname user username using psw
...rest of script...
...you can use db2 CLP commands directly
The first line sets a variable to contain the fully qualified pathname to the db2cmd.exe executable. This is the default path so you may need to change the pathname to match your environment, and you can omit this if you are certain that db2cmd.exe will always be on the system path.
The second line tests if the script is running under db2cmd.exe (in which case the DB2CLP environment
variable will be set). If the script is not running under db2cmd.exe then the script runs itself
under db2cmd.exe passing on the same command-line parameters. If the script is already running under db2cmd.exe then continue to the next line.