What is the logic behind Unix's sort command? - linux

So I'm sorting a large file that has many lines of the form:
<node_number>,<value>
The Unix command I'm using is very simple:
sort <file_name>
Here's a part of the output:
....
100009,0.000000
1000090,0.000000
100009,0.050510
1000093,0.000000
1000095,0.000000
1000095,0.000000
....
But why is:
1000090,0.000000
coming before:
100009,0.050510
even though:
100009,0.000000
was before it?
Shouldn't the order be:
....
100009,0.000000
100009,0.050510
1000090,0.000000
....
Why is this not the order in the output file?
This weird order was there in many other parts of the file.
Important Note: I know there are options for the sort command to solve this issue. My intention isn't to find those options in the sort command. I just want to understand the logic behind the current sort output.

Related

how can i make the lines variable in a file?

I am using a unix based program. I want to automate the code so as not to copy and paste data one by one. For this, I need to define line-by-line data in a file as a variable for the code
The program converts xyz coordinates to local coordinates. How can I run the coordinates in the xyz_coordinates file I created, one by one, in the code below? In the program I use, the conversion code works like this:
echo 4208830.039709186 2334850.551667509 4171267.377406844 -6.753E-01 4.493E-01 2.849E-01 | xyz2env.py
and this is the file i am trying to run:
2679689.926729193 -727950.9964290063 5722789.538975053 7.873E-02 3.466E-01 6.410E-01
2679689.927123377 -727950.9971557076 5722789.540522 7.912E-02 3.458E-01 6.425E-01
2679689.930567728 -727950.9979971027 5722789.550832021 8.257E-02 3.450E-01 6.528E-01
2679689.931029495 -727950.9992263148 5722789.549927638 8.303E-02 3.438E-01 6.519E-01
2679689.929031829 -727950.9981009626 5722789.546359798 8.103E-02 3.449E-01 6.484E-01
........
and it goes on like this. Also, there are spaces between the lines. Will this be a problem?
You can use xargs to invoke the command for a specific number of arguments (6 in your case) and have the advantage of skipping empty lines automatically
< file.txt xargs -n 6 xyz2env.py

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"

Create multiple files based on a pattern

I am interested in creating multiple files based on a simple pattern.
a.kf
b.kf
c.kf
...
fss1.lsk
fss2.lsk
fss3.lsk
...
Of course I could use a loop, however I would prefer a more elegant solution. Perhaps using the tee command, however I've had difficulty implementing this idea.
Use brace expansions.
$ touch {a..c}.kf fss{1..3}.lsk
$ ls
a.kf b.kf c.kf fss1.lsk fss2.lsk fss3.lsk

How to block-sort rows of text file in bash?

I have a bar-separated text file that looks like this:
stringC|rest-of-lineC3
stringC|rest-of-lineC1
stringC|rest-of-lineC2
stringA|rest-of-lineA2
stringA|rest-of-lineA1
stringB|rest-of-lineB4
stringB|rest-of-lineB1
stringB|rest-of-lineB3
stringB|rest-of-lineB2
I need to block-sort it by the string before the | without doing secondary sort of what comes after the bar. So the example below SHOULD be sorted into:
stringA|rest-of-lineA2
stringA|rest-of-lineA1
stringB|rest-of-lineB4
stringB|rest-of-lineB1
stringB|rest-of-lineB3
stringB|rest-of-lineB2
stringC|rest-of-lineC3
stringC|rest-of-lineC1
stringC|rest-of-lineC2
but NOT into:
stringA|rest-of-lineA1
stringA|rest-of-lineA2
stringB|rest-of-lineB1
...
Is there a way of doing this in a bash script using sort or any other commands?
How can I get the same result as above in case the original file is not in blocks, i.e. it looks something like this:
stringC|rest-of-lineC3
stringA|rest-of-lineA2
stringC|rest-of-lineC1
stringA|rest-of-lineA1
stringB|rest-of-lineB4
stringB|rest-of-lineB1
stringC|rest-of-lineC2
stringB|rest-of-lineB3
stringB|rest-of-lineB2
sort with -s option for stable
sort -st'|' -k1,1 file
initial blocks doesn't matter, should work for both.

Bash script key/value pair regardless of bash version

I am writing a curl bash script to test webservices. I will have file_1 which would contain the URL paths
/path/to/url/1/{dynamic_path}.xml
/path/to/url/2/list.xml?{query_param}
Since the values in between {} is dynamic, I am creating a separate file, which will have values for these params. the input would be in key-value pair i.e.,
dynamic_path=123
query_param=shipment
By combining two files, the input should become
/path/to/url/1/123.xml
/path/to/url/2/list.xml?shipment
This is the background of my problem. Now my questions
I am doing it in bash script, and the approach I am using is first reading the file with parameters and parse it based on '=' and store it in key/value pair. so it will be easy to replace i.e., for each url I will find the substring between {} and whatever the text it comes with, I will use it as the key to fetch the value from the array
My approach sounds okay (at least to me) BUT, I just realized that
declare -A input_map is only supported in bashscript higher than 4.0. Now, I am not 100% sure what would be the target environment for my script, since it could run in multiple department.
Is there anything better you could suggest ? Any other approach ? Any other design ?
P.S:
This is the first time i am working on bash script.
Here's a risky way to do it: Assuming the values are in a file named "values"
. values
eval "$( sed 's/^/echo "/; s/{/${/; s/$/"/' file_1 )"
Basically, stick a dollar sign in front of the braces and transform each line into an echo statement.
More effort, with awk:
awk '
NR==FNR {split($0, a, /=/); v[a[1]]=a[2]; next}
(i=index($0, "{")) && (j=index($0,"}")) {
key=substr($0,i+1, j-i-1)
print substr($0, 1, i-1) v[key] substr($0, j+1)
}
' values file_1
There are many ways to do this. You seem to think of putting all inputs in a hashmap, and then iterate over that hashmap. In shell scripting it's more common and practical to process things as a stream using pipelines.
For example, your inputs could be in a csv file:
123,shipment
345,order
Then you could process this file like this:
while IFS=, read path param; do
sed -e "s/{dynamic_path}/$path/" -e "s/{query_param}/$param/" file_1
done < input.csv
The output will be:
/path/to/url/1/123.xml
/path/to/url/2/list.xml?shipment
/path/to/url/1/345.xml
/path/to/url/2/list.xml?order
But this is just an example, there can be so many other ways.
You should definitely start by writing a proof of concept and test it on your deployment server. This example should work in old versions of bash too.

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