Just want to share with you something I did not easily find by myself...
I am a newbie in shell script and was just wondering how can I increment a value of a an associative array.
Let's assume this script:
#!/bin/bash
declare -A b # declare an associative array
a="aaa"
b[$a]=1
echo ${b[#]} # display all the values
echo ${b[$a]} # display the first value (1)
echo ${b[aaa]} # display the first value as well (1)
The solution can be
((b[$a]++))
echo ${b[#]} # display 2
Now that I found it, it seems evident, but I spent some time to get it...
I hope this can save some time to people :)
As describe above, the solution can be
((b[$a]++)) # or (('b[$a]'++)) for a more secure way as pointed by #gniourf_gniourf
echo ${b[#]} # display 2
Now that I found it, it seems evident, but I spent some time to get it...
I hope this can save some time to people :)
Related
I am currently working on a small command line interface tool that someone not very familiar with bash could run from their computer. I have changed content for confidentiality, however functionality has remained the same.
The user would be given a prompt
the user would then respond with their answer(s)
From this, I would be given two bits of information:
1.their responses now as individual variables
2.the number of variables that I have now been given: this value is now a variable as well
my current script is as follows
echo List your favorite car manufacturers
read $car1 $car2 $car3 #end user can list as many as they wish
for n in {1..$numberofmanufacturers} #finding the number of
variables/manufactures is my second question
do
echo car$n
done
I am wanting to allow for the user to enter as many car manufacturers as they please (1=<n), however I need each manufacturer to be a different variable. I also need to be able to automate the count of the number of manufacturers and have that value be its own new variable.
Would I be better suited for having the end user create a .txt file in which they list (vertically) their manufactures, thus forcing me to use wc -l to determine the number of manufacturers?
I appreciate any help in advance.
As I said in the comment, whenever you want to use multiple dynamically created variables, you should check if there isn't a better data structure for your use case; and in almost all cases there will be. Here is the implementation using bash arrays. It prints out the contents of the input array in three different ways.
echo List your favorite car manufacturers
# read in an array, split on spaces
read -a cars
echo Looping over array values
for car in "${cars[#]}"
do
echo $car
done
echo Looping over array indices
for i in ${!cars[#]}
do
echo ${cars[$i]}
done
echo Looping from 0 to length-1
let numcars=${#cars[#]}
for i in $(seq 0 $((numcars-1)))
do
echo ${cars[$i]}
done
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 < "$original_file"
I'm wondering is there anyway to use for example , or ^ or % and so on, from variables in Bash ?
in instance I have three variables
var1='hello world'
var2=${var1:3}
var3='^'
I want to do this in bash ! please attention to my question I know it's very simple in other ways but how about this ?
echo ${var1:0:3}${var2$var3} # instead of echo ${var1:0:3}${var2^}
and finally output is :
heLlo world
In theory, eval can do execute arbitrary code, but has many security issues, so it should be used as last resort. Use it only when you trust the input 100%.
var1='hello world'
var2=${var1:3}
var3='^'
eval echo '${var1:0:3}${var2'$var3'}'
count1=`cat $affected_ip|wc -l`;
echo $count1;
Will these lines of code fetch the count from the file named afffected_ip and print the output?
Need help to perform above task.
I suppose you are trying to count the number of ips affected etc, etc, whereby you have 1 ip per line.
You are not too far off actually.
First of all ( as mentioned by user simon3270 ) , you dont need thesemicolons in this snippet. Variables for assignment in bash dont need the $ too in this scenario.
In your case, running at bash shell
wc - l < affected_ips.txt
And you will get the number of lines / IPs. Grepping etc could help you if you have particular patters to discern.
Share more info if you need more help.
I'm almost completely new to Linux programming, and Bash Scripts. I build an amateur radio AllStar node.
I'm trying to create a script that looks at a certain variable and based on that info decides if it should connect or not. I can use a command: asterisk -rx "rpt showvars 47168. This returns a list of variables and their current values. I can store the whole list into a variable that I define, in my test script I just called it MYVAR but I can't seem to only get the value of one of the variables that's listed.
I talked to someone who knows a lot about Linux programming, and she suggested that I try CONNECTED="${MYVAR[3]}" but when I do this, CONNECTED just seems to become a blank variable.
What really frustrates me is I have written programs in other programming languages, and I've been told Bash scripts are easy to learn, but yet I can't seem to get this.
So any help would be great.
how did you assigned your variable?
It seems to me that you want to work with an array, then:
#!/bin/bash
myvar=( $( asterisk -rx "rpt showvars 47168 ) )
echo ${mywar[3]} # this is your fourth element
echo ${#myvar[#]} # this is the total of element in your array
be careful that index in an array starts at 0