ksh scripting problem

[david.]

I am having a problem scripting in ksh. I want to have a general subroutine which can query the version of a program. Since there are so many different ways of querying an application, I want to have the actual command passed as a string, and then used as part of a command.

I have a subroutine which has
$4 = pathname terminated with /
$5 = binary name
$6 = cmd string

Get_Version ()
{
# does not work
QUERY="`$4$5 $6`"

# works
QUERY1="`$4$5 -version | cut -f1 -d, | cut -f3 -d' '`"

echo "${QUERY} does not equal ${QUERY1}.  Why not?"
}

FX_CMD="-version | cut -f1 -d, | cut -f3 -d' '"
FX_PATH="/opt/sfw/lib/firefox"
FX_BIN="firefox-bin"

# nulls for example only
Get_Version null null null $FX_PATH $FX_BIN "$FX_CMD"

I can't figure out why the pipes and cuts don't work when I try and use a variable.

perplexed <at> paiged <dot> fea <dot> st

[lomcevak]

First, some utilities display the version on stderr and pipe only pipes stdout. So you have to redirect stderr to stdout (2>&1).

Second, if you're going to pass the command as a parameter use the eval command to execute it.

You also forgot the trailing '/' on FX_PATH.

Get_Version ()
{
# does not work
QUERY="`eval $4$5 $6`"

# works
QUERY1="`$4$5 -version 2>&1 | cut -f1 -d, | cut -f3 -d' '`"

echo "${QUERY} does not equal ${QUERY1}.  Why not?"
}

FX_CMD="-version 2>&1 | cut -f1 -d, | cut -f3 -d' '"
FX_PATH="/opt/sfw/lib/firefox/"
FX_BIN="firefox-bin"

# nulls for example only
Get_Version null null null $FX_PATH $FX_BIN "$FX_CMD"

[drl]

Hi.

You might find the ksh (and bash) builtin command command to be useful. See the man page for each for details.

If you are intending to use your function to display the version of system programs, note that many (but not all) of the GNU programs use "--version" (2 minus signs) to elicit the version of the program.

Good luck ... cheers, drl

[david.]

drl, the inconsistencies between --version and -version (or even -V) is the reason for placing the command string into a variable. I can then make the subroutine generic, generally (without) concern about how to retrieve the version information.

lomcevak, I'll try your suggestions, and see if they help.