Questions tagged [arithmetic]
This tag is meant for everything that has to do with mathematical operations. So if you want to ask a question about doing calculations in `awk`, or if you have a question about `bc`, this is the right tag to use.
210 questions
12
votes
2
answers
1k
views
Why arithmetic syntax error in bash causes exit from the function?
I was debugging one script, and discovered unexpected behavour of handling arithmetic syntax error.
Normally, when error happens, script is just continuing execution.
#!/bin/bash
func2 () {
echo &...
- 1,209
4
votes
1
answer
297
views
using the bc calculator with obase and ibase to convert integer representation
I am using the bc calculator with obase and ibase to convert integer representation.
I'm not used to it, because very basic things can be done with $(( expresion )) in bash, and most things that can't ...
- 572
2
votes
1
answer
483
views
What's the difference between '$var' and 'var' in an arithmetic expansion?
Bash accepts both these syntax:
FOO=$(($BAR + 42))
and
FOO=$((BAR + 42))
Which one is correct / most portable / less prone to errors? Or are both equally valid?
- 32.4k
-3
votes
1
answer
195
views
How to split a number into unequal parts in Bash
Hypothetic example: There is a number that I will split into x parts (smaller numbers, in a range you see in the example).
I need a way, ideally a one liner for the Linux Bash, to split a large number ...
- 539
1
vote
5
answers
271
views
how to subtract a date in format: 'xyz/[int][int]/[int][int][int][int]' from the current date?
Scenario
I have containers which have last deploy dates in the format:
month/date/year or feb/11/2024.
I cant change the way they output the last deploy date.
I'd like to subtract the last deploy date,...
- 554
-1
votes
2
answers
158
views
Numeric if conditions that read a command in a bash script
I'm trying to write a command that looks at my battery state and suspends the laptop if the battery is low. I tried using something like this:
#!/bin/bash
if [ $(acpi -b | cut -c 25) < 11 ]
then ...
0
votes
1
answer
61
views
Logging sum of Mem and Swap from free command output
In relation to this:
https://unix.stackexchange.com/a/754252/582781
Solution 1:
free -g -s2 | sed -u -n 's/^Mem:\s\+[0-9]\+\s\+\([0-9]\+\)\s.\+/\1/p' >> memory.log
Is there a way to add Swap to ...
-4
votes
1
answer
131
views
How to protect variable name inside shell arithmetic?
Variables can be protected with curly braces.
Mynewvar=1
echo $Mynewvar
1
echo ${Mynewvar}
1
However I can no longer protect them when inside shell arithmetic.
Mynewvar=1
echo $((Mynewvar+9))
10
echo ...
- 1
3
votes
4
answers
587
views
Apply arithmetic into piped command
So far I have this:
sudo find /path/to/dir -type f |
xargs -d "\n" sudo stat -c "%Y %n" |
{arithmetic to check if %Y is between 1685518962 and 1685624474??} |
{show ...
- 143
1
vote
1
answer
339
views
Arithmetic operation issue in bash script | invalid arithmetic operator
From a bash script I am downloading a file from a server using curl call. Now I want to check if the file is fully downloaded. For this I am comparing the size of downloaded file and Content-Length ...
- 223
-5
votes
1
answer
349
views
printing prime number in bash [closed]
hi i am new to programming and currnetly learing bash script.
please help with this error " line 28: expected `)' "
Given below is my program.
read -p "enter the number:" a
while [...
- 1
-1
votes
1
answer
2k
views
What is an operand?
I just want someone to explain what an "operand" is because I just don't understand it. Here is the context I'm reading this in:
In the section about Shell Arithmetic in the bash shell ...
- 895
9
votes
1
answer
11k
views
How does arithmetic expansion work with variables without the $ (dollar) sign?
I think the line below should be written differently, and the command should bug out.
$ echo $((x=2, y=3, x+y))
5
I thought the way to write this was:
$ echo $((x=2, y=3, $x+$y))
5
Both work, which ...
- 895
2
votes
1
answer
153
views
Arithmetic operation in terminal from an output
I want to print the lines of updates via this command
dnf check-update --refresh --q --downloadonly | wc -l
However during the output there occurs a blank line which means the true update number is ...
- 153
0
votes
2
answers
103
views
Unable to put output of basic calculator in a variable, formatting bytes to MB in bash
I want to get my data usage from my wifi device to display on my top bar, I can get the data usage in bytes using curl like this
$bytes=(curl -d "Page=GetWANInfo" -X POST http://jiofi.local....
- 103
0
votes
1
answer
533
views
Evaluate a integer expression in bash
I have a set of piped commands that generates an integer expression. A sample looks like (1 +(0x1f+0x02))
I can evaluate this expression (get the resulting value), by enclosing it in $(), so:
$ echo $(...
- 145
4
votes
4
answers
2k
views
Precision of the date command and arithmetic
I take a date at nanosecond precision:
$ start=$(date '+%s.%N')
...then print it:
$ echo ${start}
1662664850.030126174
So far so good. But look what I get when I printf with some arbitrarily huge ...
2
votes
3
answers
2k
views
Replicating floating point arithmetic WITHOUT bc utility
I'm needing to write a script on some embedded Linux systems that don't have bc installed on them and won't be able to have it installed. The script I'm writing is essentially a monitoring script that ...
- 43
2
votes
3
answers
926
views
Performing calculation on the contents of two files
file1 contains 100 as its content, and file2 contains 200. How would I perform calculation on those two numbers in the terminal? Say I would like to perform division on those two numbers. My approach ...
- 121
0
votes
1
answer
181
views
How to replace text in file - conditions and arithmetic required
I need a script to change content in some text files. This a bit beyond my limited bash skills. Maybe perl or python would be a better approach, I have no experience with either of these.
I have a ...
- 1
11
votes
2
answers
4k
views
bash calc returns 800 (should be 600): echo "$(( 800 / (4 / 3) ))"
I'm calculating aspect ratio height from x number, in this example I'm using 4:3 ratio, and a width of 800, the result (height) should be 600, but bash is returning 800, and I'm not sure why.
I've ...
- 265
1
vote
1
answer
296
views
Sum of timestamps in unix [closed]
I need a code to add 2 timestamps of format HH:MM:SS in unix, can anybody help?
Unfortunately, I have stored timestamp as varchar in the database, in the format (e.g.)
07:53:39
Now I want sum of that ...
- 11
0
votes
1
answer
312
views
sed giving invalid arithmetic operator error
sed keeps giving invalid arithmetic operator error. I am trying to assign the output of sed to a variable.
This one works,
var=$(sed -e 's/"currentGeneration":5010/"currentGeneration&...
- 25
-1
votes
1
answer
575
views
How to round to the correct nearest number in Linux bc?
How do we round to the correct nearest number in a Linux basic calculator BC?
user494414
2
votes
4
answers
466
views
Multiply numbers between two different patterns and print the whole file
I would like to replace number between patterns with multiplicated numbers and print the all the lines.
The file is a tree file in newick format and consisted only a single line. My targets are all ...
- 193
7
votes
3
answers
4k
views
Handling 64-bit integers in a shell script
I am trying to calculate the used bandwidth on the Ethernet interface (which is 1000 Mbit/s). To test my script, I am using the iperf tool to generate huge bandwidths.
The problem I am facing is when ...
- 63
0
votes
3
answers
634
views
Is parameter expansion in test expression possible?
When I try the following expression in bash I get a strange error message:
[: -lt: unary operator expected
First the function definition
some_func () {
(( 3 + 5 ))
}
And the expression
[ $(...
- 515
3
votes
2
answers
1k
views
Check if a number is in a range with zsh
Why is passing 0 as an argument results in a false positive (prints "True")?
#!/bin/zsh
k="$1"
if ((0 < k < 1))
then
echo "True"
fi
Note this script is ...
- 41
1
vote
2
answers
361
views
How bash interprets triple parentheses?
I see that in bash the command
echo $(((i=18)))
prints 18.
This makes me understand that $(((i=18))) is interpreted as an arithmetic expansion (with the variable i being initialized inside the ...
- 89
9
votes
4
answers
3k
views
Bitwise operations in Bash not working as expected
I ran into a strange problem. To demonstrate, let's take the largest unsigned number on my machine (printf "%X \n" -1 gives me FFFFFFFFFFFFFFFF), and try to shift some bits. First, shift ...
- 1,954
11
votes
3
answers
3k
views
Find the largest number that Bash arithmetic can handle?
How can I let my script determine the largest number for itself?
I looked through my environment variables, and I found these two that looked promising:
~# declare -p BASH_VERSINFO HOSTTYPE
declare -...
user461766
1
vote
2
answers
218
views
Arithmetic between 2 files generating a series of new files using awk
I have a tab separated model input file i would like to vary for ensemble analysis formatted such as this
cat input.txt
#############################################
### Parameter file for the ...
- 75
0
votes
1
answer
71
views
Arithmetic between 2 files generating a series of new files (Pt 3)
I have a tab separated model input file I would like to vary for an ensemble analysis formatted similar to this
cat input.txt
/* Precipitation in mm */
10 30 15 20 ...
- 75
0
votes
1
answer
66
views
Arithmetic between 2 files generating a series of new files (Pt 2)
This is a more specific follow-up to a previous question (Arithmetic between 2 files generating a series of new files).
I have a tab separated model input file I would like to vary for an ensemble ...
- 75
2
votes
6
answers
166
views
Arithmetic between 2 files generating a series of new files
I have a tab separated model input file I would like to vary for an ensemble analysis formatted similar to this
input.txt
/* Preciptation in mm */
10 30 40 50 23
### Species description
*** sp_name ...
- 75
0
votes
2
answers
57
views
addition by specific value of arithmetic values presented in file1 to file2
I have in file 1 the following
'a 62-182'
'a 183-303'
'a 304-424'
...
is there any way I can have based on file1's value the following in file 2?
'a 62-182' 'a 7195-7315'
'a 183-303' 'a 7316-7436'
...
- 543
4
votes
1
answer
374
views
In ZSH, what arithmetic expressions can appear as array subscript?
The ZSH manual (zshparam(1)) reads:
Array Subscripts
Individual elements of an array may be selected using a subscript. A
subscript of the form `[exp]' selects the single element exp, ...
- 844
0
votes
3
answers
3k
views
Divide by zero exception using awk
i have values stored in variables var1=6 and var2=4, i am trying to divide them with a precision of 2 and store the result in a variable var,
var=`awk 'BEGIN {printf "%.2f\n", $var1/ $var2}'`...
0
votes
0
answers
17
views
BASH: arithmetic expressions on point values [duplicate]
I am looking for bash function suitable to do some simple arithmetic expressions on point values
For intance
i=1
let "i_mod=${i}+1"; echo $i_mod
gives me 2
but if
i=1.0
let "i_mod=${i}+...
- 213
10
votes
6
answers
2k
views
Arithmetic on values with memory size units
Let’s say I have a bunch of numbers representing quantities of memory, written in the form 86k or 320m or 1.7g for instance. How can I compute their sum in command line, and get back a human-readable ...
- 446
1
vote
3
answers
814
views
How do I sum up the results of multiple bash commands in bash?
So I've got the following
cat a1 | wc -l // term1
cat a2 | wc -l // term2
cat a3 | wc -l // term3
...
cat a10 | wc -l // term10
And I'd like to calculate term1 + term2 + ... + term10 in a one liner (...
- 147
0
votes
2
answers
632
views
Rounding numbers of a CSV file, skipping the header
This question is a derivative of the https://askubuntu.com/questions/601149/is-there-a-command-to-round-decimal-numbers-in-txt-files, which was successfully solved by using:
perl -i -pe 's/(\d*\.\d*)/...
- 93
-3
votes
3
answers
309
views
Bash script - How is 6 > 50? [duplicate]
if [[ 6 > 50 ]]; then
echo "true"
fi
$ bash script.sh
I'm missing something very obvious here. Why is 6 greater than 50 ??
** EDIT **
I'm also try to solve for
if [[ 6.5 > 50 ]]; ...
- 201
7
votes
4
answers
2k
views
Why does the command a-=2 fail?
After executing the command declare -i a=5, the command a+=2 succeeds, but the command a-=2 fails. Can someone explain this strange behavior of bash?
- 793
0
votes
1
answer
490
views
Sum all media durations in current folder
I had a bunch of media (videos to be precise) in a folder and I wanted to sum all the lenghts. I'll be ignoring seconds and hours for now, just to get the gist of it. I wrote this script:
sum=0
for ...
- 125
1
vote
2
answers
2k
views
Sum of large numbers and print the result with all decimal points for the stated question when using awk arrays
I have a below input file which I need to split into multiple files based on the date in 3rd column. Basically all the same dated transactions should be splitted into particular dated file. Post ...
- 83
2
votes
4
answers
5k
views
Sum all positive integers in a bash array
How can I sum all positive integers in a bash array.
Here is my code:
#!/bin/bash
arr=(2 43 -1 -33 24 12 -6)
for (( i = 0; i < ${#arr[@]}; ++i )); do
if (( arr[i] > 0 )); then
sum=`...
0
votes
2
answers
1k
views
awk column-wise division of all lines by another line
I'm trying to divide all lines in file1.txt by their respective (column-wise) value in the single line in file2.txt.
cat file1.txt
1 2.5 3
7 7 7
1 3 5
cat file2.txt
...
- 3
1
vote
2
answers
617
views
Bash: Arithmetic expansion, parameter expansion, and the comma operator
I have a question about bash's parameter expansion, inside a comma expression, inside an arithmetic expression. I have two statements that I thought should be equivalent, but they're not.
Why does ...
- 158
0
votes
2
answers
5k
views
How to resolve Illegal number: -1.00 | ubuntu
I have a scenario where I am taking difference of two numbers.
Then the calculated difference needs to be checked within a range.
If it lie within that range then display status as success, else ...
