Command Processor Quirk?
The other day, while I was creating a new utility command to use with PC Support, I came across a strange quirk of the command processor. I defined a parameter as type *CHAR, 64 characters long, so it would accept a complete PC path, including the file name with its extension.
It turns out, however, that the backslash character () is considered an invalid character, unless you enclose the path in single quotes. This means that I could not type SUBDIRFILENAME.EXT in the parameter, but had to enclose it in single quotes. That's not all, though. The worst part is how the command processor treats an unquoted colon character (:).
First, I wanted to specify A: in the path parameter, so I typed in an A and a colon. I kept getting "Invalid directory" messages from DOS and, since DOS doesn't give much detail in its error messages, I was stumped until I started debugging and threw in a breakpoint. The command processor had removed the colon. Further testing revealed the following:
o If you type a colon at the end of an unquoted string, the command processor removes the colon.
o If you type a colon at the end of a quoted string, the command processor preserves the colon.
o If you prompt for the command and type an unquoted string that has an embedded blank and ends in a colon, the colon is preserved because in this case the command prompter supplies the quotes, turning the string into a quoted string.
If the above steps are repeated using a parameter of type *CMDSTR (command string), the results are different:
o Ending colons are always preserved.
o If you type an embedded colon, the portion of the command string prior to the colon is assumed to be a label (as in a CL program) and the portion after the colon is assumed to be a valid command name. If the command doesn't exist, you get an error message.
o If you embed two or more colons, you get an error message because there's more than one label in the command.
o Backslash characters are invalid in command parameters, in the portion before the first blank (which is assumed to be the command name) and in unquoted command parameters.
I can understand about the backslashes being invalid characters, but why isn't the colon treated the same way? It took me a while to find the source of the problem, and I can find no circumvention. To this day, I have to make sure I enclose in quotes the PC path in my custom PC Support commands. I've included a simple command and its processing program (Figures 1 and 2) for you to try out this quirk.
TechTalk: Command Processor Quirk?
Figure 1 Command #EM002
/* */ /* To compile: */ /* */ /* CRTCMD CMD(XXX/#EM002) PGM(XXX/#EM002CL) + */ /* SRCFILE(XXX/QCMDSRC) */ /* */ #EM002: CMD PROMPT('Test Command') PARM KWD(CHAR) TYPE(*CHAR) LEN(32) + PROMPT('Character') PARM KWD(CMD) TYPE(*CMDSTR) LEN(32) + PROMPT('Command')
TechTalk: Command Processor Quirk?
Figure 2 CL Program #EM002CL
/* */ /* To Compile: */ /* */ /* CRTCLPGM PGM(XXX/#EM002CL) SRCFILE(XXX/QCLSRC) */ /* */ #EM002CL: PGM PARM(&CHAR &CMD) DCL VAR(&CHAR) TYPE(*CHAR) LEN(32) DCL VAR(&CMD) TYPE(*CHAR) LEN(32) SNDPGMMSG MSG('Char =' *BCAT &CHAR) MSGTYPE(*INFO) SNDPGMMSG MSG('Cmd =' *BCAT &CMD) MSGTYPE(*INFO) ENDPGM
More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.
TRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now! Request Now.
Forms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.
Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:
Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.
IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn:
LATEST COMMENTS
MC Press Online