How to combine two commands into one under unix?

Question

Usually i start debug a java program by type jdb in terminal, then it will enter debugging mode, then i can input something like "stop at com.android.contacts.dirtyImport.DirtyImportManager:95" to tell jdb to stop at certain line.

Now here is the question: how can i combine these two cmds input one. Something like "jdb < stop at com.android.contacts.dirtyImport.DirtyImportManager:95". The reason i have this requirement is that i want to let vim automatic generate debug info and enter debug mode, stop make breakpoint.

thiton · Accepted Answer · 2012-05-16 08:05:13Z

3

One option is to prepend a line to the standard input:

{ echo "stop at com.android.contacts.dirtyImport.DirtyImportManager:95"; cat; } | jdb

This starts a subshell ({}) that first prints the given line with echo and then reads the standard input and prints the read lines to the standard output (cat). The whole input is piped into jdb.

This, however, confuses some programs that distinguish between terminal input and pipe input. In this case, you'll want to have a look at the program's reference, as debuggers often support executing commands from a file (as gdb with -x).

edited May 16, 2012 at 8:05

answered May 15, 2012 at 9:45

thiton

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2 Comments

Frank Cheng Over a year ago

Can i plus this answer twice? You are totally a genius. I have searching this answer so long. But i still don't know what does { and cat used for? Could you give me any hints? Because after i remove any part of your command i won't run as i wish. Thank you again.

thiton Over a year ago

@user674199: Thanks. Expanded the answer.

Zsolt Botykai · Accepted Answer · 2012-05-15 09:39:02Z

0

I'm not sure but you might looking into generating expect scripts. Here is a tutorial, which does something with gdb automation.

answered May 15, 2012 at 9:39

Zsolt Botykai

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