Shell Programming and Scripting

Not quite sure what you are asking, so I'm guessing here...
The construct varname=$(command) executes the command and assigns the output to the variable. This style obsoletes back quotes, or back ticks.

If you were asking something else, please ask. If I don't get back to it first, someone will likely post an answer.

Ohhh, thanks, I completely forgot about the need for back ticks thing. Do you know if the $ thing will work in most shells or just particular newer ones. Are the parenthesis needed?

Parens are certainly necessary. Works in modern Kshell and bash.

I rarely use bash, so I cannot say how far back it is supported. The version I have loaded on this machine is GNU bash, version 3.2.39(1)-release (i586-suse-linux-gnu) and it works.

I usually live on the edge with Kshell's latest release and have been using $(command) now for several years. I would doubt that you'll run into an instance that doesn't support it.

I really cannot speak for other sh like shells, so maybe, but maybe not.

cant seem to get ifthanwhile's example working. When i execute the shell script i get the following.

Code:

./cc.sh: line 8: syntax error near unexpected token `)'
./cc.sh: line 8: `    2) echo 'test2/' >> mtest.txt'

Here is my script.

Code:

#!/bin/bash

nscripts=2
rn=$(( $RANDOM % $nscripts ))

case $rn in
    1) echo 'test1/' >> mtest.txt
    2) echo 'test2/' >> mtest.txt
esac
exit 0

By changing the ) to backslashes i get it to somewhat work, but it doesn't copy the test1 text to the end of the file it copies that everything after it and everything until the / on the next line.

---------- Post updated at 06:06 PM ---------- Previous update was at 12:38 AM ----------

Still cant get it working, ive tried multiple things. I know its a very simple script but im to new to shell scripting to troubleshoot this.

There are two issues. First, the result of your mod operation (%) will be 0 through n-1, or in your case either 0 or 1. You need to adjust your case accordingly.

The problem that is causing the odd output is that you are missing the 'termination' semicolon pair at the end of each case action:

Code:

#!/bin/bash

nscripts=2
rn=$(( ($RANDOM % $nscripts)+1 ))

case $rn in
    1) echo 'test1/' >> mtest.txt;;
    2) echo 'test2/' >> mtest.txt;;
esac

If you were to run your script through ksh or bash with the -n option, it would identify the area of the problem. Bash reports this:

Code:

spot; bash -n t2
t2: line 8: syntax error near unexpected token `)'
t2: line 8: `    2) echo 'test2/' >> mtest.txt'

From experience, the unexpected ')' message means that the ';;' was dropped from the previous block. We all occasionally leave them out, or accidentally delete them while editing.

Hope this gets you going again.

Awseome, works well

So i assume where i have mtest.txt i can also jsut specify a path to a directy containing a tex file, like the following. home/test/user/mtest.txt.

Thank you for your help, i really appreciate it

Glad it is working for you. Yes, any path to a file will work.