dbx: Error checking initialization failed ??

How to Run:
                           dbx <binaryname>

Enabling access checking :   in dbx prompt enter :  check -access
Enabling memory leak checking: in dbx prompt enter: check -memuse
Enable all checks :  in dbx prompt enter : check -all

once this is done use run command with appropriate  command line arguments to run the program.
if there are any leaks are access errors present in the binary, an error file (binary.err) will be generated and all errors will be redirected to that file.

Some times if access/memory checks are enabled, system may give errors because of some libraries used by the binary.

Ex:

(dbx) check -access
access checking - ON
(dbx) run 1
Running: a.out 1
(process id 17010)
Reading rtcapihook.so
Reading rtcaudit.so
Reading libmapmalloc.so.1
Reading libc_psr.so.1
Reading rtcboot.so
Reading librtc.so
RTC: Enabling Error Checking...
dbx: internal warning: rtc: ld/st instruction uses %r6 at 0xd55c2388 in `/bghux018/bgh26882/AMS80/FSS_MDS/contrib/lib/libnnz10.so`SHATransform_SOL
dbx: system error: cannot recover; Access checking disabled
dbx: Error checking initialization failed.  All error checking disabled.

(dbx)

here because of libnnz10.so, access check is disabled by dbx. 
to tell dbx not use that library use 'rtc skip' command. and enable the access check and run the process.

(dbx) rtc skip libnnz10.so

RTC: please turn on access checking first

(dbx) check -access

access checking - ON

(dbx) rtc skip libnnz10.so

(dbx) run 1

Running: a.out 1

(process id 17046)

RTC: Enabling Error Checking...

RTC: Using UltraSparc trap mechanism

RTC: See `help rtc showmap' and `help rtc limitations' for details.

RTC: Running program...

When access checking is turned on, RTC detects and reports the following kinds of errors:

        baf     # Bad free
        duf     # Duplicate free
        maf    # Misaligned free
        mar    # Misaligned read
        maw   # Misaligned write
        oom    # Out of memory
        rua     # Read from unallocated memory
        rui      # Read from uninitialized memory
        wro    # Write to read-only memory
        wua    # Write to unallocated memory

With leaks checking, RTC will report the following kinds of errors:


        aib     # Possible memory leak - only pointer points in the middle of the block
        air     # Possible memory leak - pointer to the block exists only in register
        mel   # Memory leak - no pointers to the block

Memory errors can be suppressed. The following command suppress read from uninitialized (rui) in all functions in a.out

(dbx) suppress rui in a.out

RTC instruments memory access assembly instructions for access checking. You can exclude load objects, object files and functions from being instrumented. The following command

(dbx) rtc skippatch a.out -f main

excludes the function main from being instrumented.

Ref : https://blogs.oracle.com/janitor/entry/runtime_memory_checking

bcheck reference : http://docs.oracle.com/cd/E19205-01/820-4180/man1/bcheck.1.html

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Extract particular lines from a file using 'sed'

1. Extract Using Line Numbers :

1 2 3

sed -n '10'p <filename> #Prints 10th line of file sed -n '10,20'p <filename> #Print lines 10 to 20 sed -n '10,$'p <filename> #Print lines 10 to end

$ sed -n '10'p file is equivalent to  
$ sed '10!d' file and results
Line 10

The default output behavior is to print every line of the input file stream.The explicit 10p command just tells it to print the tenth line
So in the first example since sed is called with -n flag, it suppress the default output and prints 10th line
in the  second example, (note -n is not used) sed will delete (d) the line if it is not (!) line number 10

Similarly printing lines from 2 to 4 :

1 2	sed -n '2,4'p file sed '2,4!d' file

Line 2
Line 3
Line 4


2. Extract Using Pattern :

Some time we may need to print the lines which matches the pattern. that also can be done using sed

1	sed -n '/main/p' check.cpp

will print the lines which matches the pattern main in check.cpp file.
grep can be used as an alternative

similarly instead of 'p' (print), 'd' (delete) can be used to delete the line matching the pattern from the file.

1	sed '/main/d' check.cpp > newfile.cpp

3. Extract non empty lines :

Following will remove the empty lines from the file. and redirect remaining to new file.

1 2	sed '/./!d' check.cpp > newfile.cpp sed '/^$/d' check.cpp > newfile.cpp

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Useful aliases in Shell

Like 'ddd' , we can see the code while debugging with gdb too ... 
Set the '-tui' flag for gdb to enable this feature. and '-quiet' will suppress copyright messages. 
      
  alias gdb='gdb -tui -quiet'

Read as many as possible without scrolling

alias tail='tail -n $((${LINES}-2))'

Reading hex data
what most people want from od

alias od='od -Ad -tx1 -v'

Create a directory and go into it

md () { mkdir -p "$1" && cd "$1"; }

Write these functions in bashrc file,common in other languages, available in the shell

ord() { printf "0x%x\n" "'$1"; }

chr() { printf $(printf '\\%03o\\n' "$1"); }

Ex Usage:

dinesh@ubuntu:~$ chr 65
A
dinesh@ubuntu:~$ ord a
0x61
dinesh@ubuntu:~$ ord 1
0x31
dinesh@ubuntu:~$ 

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