Cannot append to a file: Append replaces the content - linux

The following command does not append but replaces the content
echo 0 >> /sys/block/nvme0n1/queue/nomerges
I don't want to replace but append. But I'm curious Is there something special about this file?
It also doesn't allow more than one character as its input.

Look at https://serverfault.com/questions/865787/what-does-the-nomerge-mean-in-linux-system
It might help you in understanding, that there are only 3 options that the file can take.
Also:
nomerges enables the user to disable the lookup logic involved with IO
merging requests in the block layer. By default (0) all merges are
enabled. When set to 1 only simple one-hit merges will be tried. When
set to 2 no merge algorithms will be tried (including one-hit or more
complex tree/hash lookups).

Related

Dynamic test tag pattern execution in karate [duplicate]

I'm wondering if you can use wildcard characters with tags to get all tagged scenarios/features that match a certain pattern.
For example, I've used 17 unique tags on many scenarios throughout many of my feature files. The pattern is "#jira=CIS-" followed by 4 numbers, like #jira=CIS-1234 and #jira=CIS-5678.
I'm hoping I can use a wildcard character or something that will find all of the matches for me.
I want to be able to exclude them from being run, when I run all of my features/scenarios.
I've tried the follow:
--tags ~#jira
--tags ~#jira*
--tags ~#jira=*
--tags ~#jira=
Unfortunately none have given my the results I wanted. I was only able to exclude them when I used the exact tag, ex. ~#jira=CIS-1234. It's not a good solution to have to add each single one (of the 17 different tags) to the command line. These tags can change frequently, with new ones being added and old ones being removed, plus it would make for one real long command.
Yes. First read this - there is this un-documented expression-language (based on JS) for advanced tag selction based on the #key=val1,val2 form: https://stackoverflow.com/a/67219165/143475
So you should be able to do this:
valuesFor('#jira').isPresent
And even (here s will be a string, on which you can even do JS regex if you know how):
valuesFor('#jira').isEach(s => s.startsWith('CIS-'))
Would be great to get your confirmation and then this thread itself can help others and we can add it to the docs at some point.

Best way to identify similar text inside strings?

I've a list of phrases, actually it's an Excel file, but I can extract each single line if needed.
I need to find the line that is quite similar, for example one line can be:
ANTIBRATING SSPIRING JOINT (type 2) mod. GA160 (temp.max60°)
and some line after I can have the same line or this one:
ANTIBRATING SSPIRING JOINT (type 2) mod. GA200 (temp.max60°)
Like you can see these two lines are pretty the same, not equal in this case but at 98%
The main problem is that I've to process about 45k lines, for this reason I'm searching a way to do that in a quick and maybe visual way.
The first thing that came in my mind was to compare the very 1st line to the 2nd then the 3rd till the end, and so on with the 2nd one and the 3rd one till latest-1 and make a kind of score, for example the 1st line is 100% with line 42, 99% with line 522 ... 21% with line 22142 etc etc...
But is only one idea, maybe not the best.
Maybe out there's already a good program/script/online services/program, I searched but I can't find it, so at the end I asked here.
Anyone knows a good way (if this is possible) or script or one online services to achieve this?
One thing you can do is write a script, which does as follows:
Extract data from csv file
Define a regex which can conclude a similarity, a python example can be:
[\w\s]+\([\w]+\)[\w\s]+\([\w°]+\)
Or such, refer the documentation.
The problem you have is that you are not looking for an exact match, but a like.
This is a problem even databases have never solved and results in a full table scan.
So we're unlikely to solve it.
However, I'd like to propose that you consider alternatives:
You could decide to limit the differences to specific character sets.
In the above example, you were ignoring numbers, but respected letters.
If we can assume that this rule will always hold true, then we can perform a text replace on the string.
ANTIBRATING SSPIRING JOINT (type 2) mod. GA160 (temp.max60°) ==> ANTIBRATING SSPIRING JOINT (type _) mod. GA_ (temp.max_°)
Now, we can deal with this problem by performing an exact string comparison. This can be done by hashing. The easiest way is to feed a hashmap/hashset or a database with a hash index on the column where you will store this adjusted text.
You could decide to trade time for space.
For example, you can feed the strings to a service which will build lots of different variations of indexes on your string. For example, feed elasticsearch with your data, and then perform analytic queries on it.
Fuzzy searches is the key.
I found several projects and ideas, but the one I used is tree-agrep, I know that is quite old but in this case works for me, I created this little script to help me to create a list of differences, so I can manually check it with my file
#!/bin/bash
########## CONFIGURATIONS ##########
original_file=/path/jjj.txt
t_agrep_bin="$(command -v tre-agrep)"
destination_file=/path/destination_file.txt
distance=1
########## CONFIGURATIONS ##########
lines=$(grep "" -c "$original_file")
if [[ -s "$destination_file" ]]; then
rm -rf "$destination_file"
fi
start=1
while IFS= read -r line; do
echo "Checking line $start/$lines"
lista=$($t_agrep_bin -$distance -B --colour -s -n -i "$line" $original_file)
echo "$lista" | awk -F ':' '{print $1}' ORS=' ' >> "$destination_file"
echo >> "$destination_file"
start=$((start+1))
done < "$original_file"

Changing BUNIT in csh for a FITS file

I'm writing code in .csh, and I'm trying to change the bunit header for a FITS file from K (kelvin) to km/s. How can I do that?
I know in Python I would use new_fitsfile.header['BUNIT']='km/s', but that won't work in the current .csh code, and it's not an option to switch it to Python code.
If this is needed only once, call interactively fv or ds9, move to the header, edit the header card and save the result.
For generic batch jobs, one needs some online FITS editor like fmodhead fmodhead, fthedit, or my fedithead
sed "s:BUNIT = 'K ':BUNIT = 'km/s ':g" old.fits >new.fits
and be very careful to count the significant spaces.

Filename manipulation in cygwin

I am running cygwin on Windows 7. I am using a signal processing tool and basically performing alignments. I had about 1200 input files. Each file is of the format given below.
input_file_ format = "AC_XXXXXX.abc"
The first step required building some kind of indexes for all the input files, this was done with the tool's build-index command and now each file had 6 indexes associated with it. Therefore now I have about 1200*6 = 7200 index files. The indexes are of the form given below.
indexes_format = "AC_XXXXXX.abc.1",
"AC_XXXXXX.abc.2",
"AC_XXXXXX.abc.3",
"AC_XXXXXX.abc.4",
"AC_XXXXXX.abc.rev.1",
"AC_XXXXXX.abc.rev.1"
Now, I need to use these indexes to perform the alignment. All the 6 indexes of each file are called together and the final operation is done as follows.
signal-processing-tool ..\path-to-indexes\AC_XXXXXX.abc ..\Query file
Where AC_XXXXXX.abc is the index associated with that particular index file. All 6 index files are called with **AC_XXXXXX.abc*.
My problem is that I need to use only the first 14 characters of the index file names for the final operation.
When I use the code below, the alignment is not executed.
for file in indexes/*; do ./tool $file|cut -b1-14 Project/query_file; done
I'd appreciate help with this!
First of all, keep in mind that $file will always start with "indexes/", so trimming first 14 characters would always include that folder name in the beginning.
To use first 14 characters in a variable, use ${file:0:14}, where 0 is the starting string index, and 14 is the length of the desired substring.
Alternatively, if you want to use cut, you need to run it in a subshell: for file in indexes/*; do ./tool $(echo $file|cut -c 1-14) Project/query_file; done I changed the arg for cut to -c for characters instead of bytes

Perl program structure for parsing

I've got question about program architecture.
Say you've got 100 different log files with different formats and you need to parse and put that info into an SQL database.
My view of it is like:
use general config file like:
program1->name1("apache",/var/log/apache.log) (modulename,path to logfile1)
program2->name2("exim",/var/log/exim.log) (modulename,path to logfile2)
....
sqldb->configuration
use something like a module (1 file per program) type1.module (regexp, logstructure(somevariables), sql(tables and functions))
fork or thread processes (don't know what is better on Linux now) for different programs.
So question is, is my view of this correct? I should use one module per program (web/MTA/iptablat)
or there is some better way? I think some regexps would be the same, like date/time/ip/url. What to do with that? Or what have I missed?
example: mta exim4 mainlog
2011-04-28 13:16:24 1QFOGm-0005nQ-Ig
<= exim#mydomain.org.ua** H=localhost
(exim.mydomain.org.ua)
[127.0.0.1]:51127 I=[127.0.0.1]:465
P=esmtpsa
X=TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32
CV=no A=plain_server:spam S=763
id=1303985784.4db93e788cb5c#mydomain.org.ua T="test" from
<exim#exim.mydomain.org.ua> for
test#domain.ua
everything that is bold is already parsed and will be putted into sqldb.incoming table. now im having structure in perl to hold every parsed variable like $exim->{timstamp} or $exim->{host}->{ip}
my program will do something like tail -f /file and parse it line by line
Flexability: let say i want to add supprot to apache server (just timestamp userip and file downloaded). all i need to know what logfile to parse, what regexp shoud be and what sql structure should be. So im planning to have this like a module. just fork or thread main process with parameters(logfile,filetype). Maybe further i would add some options what not to parse (maybe some log level is low and you just dont see mutch there)
I would do it like this:
Create a config file that is formatted like this: appname:logpath:logformatname
Create a collection of Perl class that inherit from a base parser class.
Write a script which loads the config file and then loops over its contents, passing each iteration to its appropriate handler object.
If you want an example of steps 1 and 2, we have one on our project. See MT::FileMgr and MT::FileMgr::* here.
The log-monitoring tool wots could do a lot of the heavy lifting for you here. It runs as a daemon, watching as many log files as you could want, running any combination of perl regexes over them and executing something when matches are found.
I would be inclined to modify wots itself (which its licence freely allows) to support a database write method - have a look at its existing handle_* methods.
Most of the hard work has already been done for you, and you can tackle the interesting bits.
I think File::Tail is a nice fit.
You can make an array of File::Tail objects and poll them with select like this:
while (1) {
($nfound,$timeleft,#pending)=
File::Tail::select(undef,undef,undef,$timeout,#files);
unless ($nfound) {
# timeout - do something else here, if you need to
} else {
foreach (#pending) {
# here you can handle log messages depending on filename
print $_->{"input"}." (".localtime(time).") ".$_->read;
}
(from perl File::Tail doc)

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