Hi all,
My boss wants me to find out how often e-m users are accessing their account:confused:. The mail server keeps log of all logins. I want to use grep the 'usernames', but it should come out the moment it first encounters the username in the log. Can I do that? I want to avoid 10+ greps... (2 Replies)
Hello every one, I have read a little about SED and GREP but I do not know how to do this:
Using SED or GREP:
"reverse all three letter words"
"replace the last two digits in any string of digits by zeros (0)"
"remove lines that start and end with the same word"
and I have more like... (5 Replies)
I have the data file:
A
1
2
3
BBB
4
5
6
A
7
8
9
I want to grep "A" then-skip a line-then-add two sublines:
I my command:
grep +3 "A" datafile (8 Replies)
Hello All,
I have few of questions related to Grep given below:
1. Like Perl, is it possible in Grep to negate characters in square brackets. For example in Perl, if '^' is used inside '' then it acts as a negation characters. Can same be achieved through Grep's regular expression.
2. How... (9 Replies)
Hi guys. I need to filter some values from a number of log files. One of the files is:
Interconnect Utilisation Results:
Achieved Maximum Number of Concurrent Connections: 17
Statistics for Average Number of Concurrent Connections:
Point Estimation: Confidence Interval: ... (2 Replies)
This post was previously mistaken for homework, but is actually a small piece of what I working on at work. Please answer if you can.
QUESTION1
How do you grep only an exact string. I am using Solaris10 and do not have any GNU products installed.
Contents of car.txt
CAR1_KEY0
CAR1_KEY1... (2 Replies)
I have different things that I was trying to do but am kind of struggling with this since I'm a Linux noob. The backround is that I have two files with student names in the same directory, and each file lists the student name, their major and their grade level. What is the most efficient way to... (6 Replies)
Hi. I have a txt file. I need to make a copy of the lines which are beginning with a mobile phone number, or a fix phone number. I have to copy thoose lines in numbers.txt, after that i have to delete then from the originally file. In numbers.txt i need to write a prefix before each number. if the... (1 Reply)
1. The problem statement, all variables and given/known data:
So i'll probably get told off for this but I have a few problems and rather than clog up the whole forum I'll post them here. Please bare in mind I am a complete novice when it comes to all this and so if you help please treat me like a... (4 Replies)
Discussion started by: jamesb18
4 Replies
LEARN ABOUT CENTOS
error::dwarf
ERROR::DWARF(7stap)ERROR::DWARF(7stap)NAME
error::dwarf - dwarf debuginfo quality problems
DESCRIPTION
Systemtap sometimes relies on ELF/DWARF debuginfo for programs being instrumented to locate places to probe, or context variables to
read/write, just like a symbolic debugger does. Even though examination of the program's source code may show variables or lines where
probes may be desired, the compiler must preserve information about them for systemtap (or a debugger such as gdb) to get pinpoint access
to the desired information. If a script requires such data, but the compiler did not preserve enough of it, pass-2 errors may result.
Common conditions that trigger these problems include;
compiler version
Prior to GCC version 4.5, debuginfo quality was fairly limited. Often developers were advised to build their programs with -O0 -g
flags to disable optimization. GCC version 4.5 introduced a facility called "variable-tracking assignments" that allows it to gen-
erate high-quality debuginfo under full -O2 -g optimization. It is not perfect, but much better than before. Note that, due to
another gcc bug (PR51358) -O0 -g can actually sometimes make debuginfo quality worse than for -O2 -g.
function inlining
Even modern gcc sometimes has problems with parameters for inlined functions. It may be necessary to change the script to probe at
a slightly different place (try a .statement() probe, instead of a .function() probe, somewhere a few source lines into the body of
the inlined function. Or try putting a probe at the call site of the inlined function. Or use the if @defined($var) { ... } script
language construct to test for the resolvability of the context variable before using it.
instruction reordering
Heavily optimized code often smears the instructions from multiple source statements together. This can leave systemtap with no
place to choose to place a probe, especially a statement probe specified by line number. Systemtap may advise to try a nearby line
number, but these may not work well either. Consider placing a probe by a statement wildcard or line number range.
ALTERNATIVES
In order to reduce reliance on ELF/DWARF debuginfo, consider the use of statically compiled-in instrumentation, such as kernel tracepoints,
or <sys/sdt.h> userspace markers. Such instrumentation hook sites are relatively low cost (just one NOP instruction for sdt.h), and nearly
guarantee the availability of parameter data and a reliable probe site, all without reliance on debuginfo.
SEE ALSO stap(1),
http://dwarfstd.org/,
http://sourceware.org/systemtap/wiki/TipContextVariables,
http://gcc.gnu.org/wiki/Var_Tracking_Assignments,
warning::debuginfo(7stap),
error::reporting(7stap)ERROR::DWARF(7stap)