How can I calculate the percentage of RGB values in an image using Linux? I’ve done some research and it appears that C# and Python may be the way to go. Answer Let ImageMagick generate a histogram for you showing how many pixels there are of each colour, So, say you have have an image called image.jpg, or image.png, like
Tag: unix
How does tmux, vim, emacs, etc transcend the UI limitations of *nix terminals?
When I’m writing a program for use on the command line, I notice that there’s some limitations. For instance, I can’t draw a 1-pixel-thick horizontal or vertical line like tmux does when it separates panes in a window. I can only move the cursor down, not up like VI seemingly does. I can’t refresh information on the top of the
If a File is Empty, Write Text to First Line
I need to check to see if two files are empty. If they are, then write “-999” to the file, else run an average on the numbers within the file. Here is the coding I’ve been trying to use: Code: Contents of file_all: Answer the appropriate way to check whether a file is empty is using -s not -z (which
How to compute Cumulative values in Shell?
I would like to compute cumulative values from the below data file and writing them into columns after inserting a serial number. Where ifile.txt has 3 rows and 9 columns in this example. Desire output: Here first column is used for the serial number. So what I did is: I first converted into columns using Then I use awk I
Use of $- in shell script
What is use of $- in Unix. In My system, the output is, what is meant by himBH? what it stands for. Thanks in Advance… Answer It returns the current shell’s flags. The $- variable contains the shell’s flags currently active in your terminal. These flags determine how your shell will function for you. In your case, these flags have
Where & How is user group information stored in Ubuntu?
Mirror Question: https://unix.stackexchange.com/questions/217300/where-how-is-user-group-information-stored-in-ubuntu. (I’ll remove one of them after I got the answer) Two places possible: /etc/group and /etc/passwd. If I use command: adduser [username] [groupname], then the user would be added to the group, and the file /etc/group would then be updated. However, the file /etc/passwd is not updated. if I check which group I belongs to, via groups
How to identify directory paths within multi-line string, replace with references to own file content, in Bash?
Given a bash variable containing the following multi-line string representing *nix paths: I’d like to be able to identify all directories (dir1 & dir2, for example) and to replace these directory path lines with the paths of the files below them. There should be no directory references in the final output, thus: I’m not sure exactly how to iterate over
Calculate Median and Average of a Text FIle with Multiple Columns of Data
I have a file with multiple columns of data. I need to calculate the median and average of the two columns. Input: Desired Output: I have tried Which is good for only one column of data. Answer Here I’m assuming you meant to work with columns and calculate two sets of values. Your output format is not reflecting this assumption
Linux: Extract a specified number of lines from text file based on match
I have a text file with multiple datasets. I have written a code that searches for certain values (top left 4-letter code) in a text file but, now I need to be able to have the script copy out data from a set number of lines AFTER the match (“PHHI, etc”) is found. The data values are all formatted the
How to echo a dynamic variable’s content in shell script
How to echo a dynamic variable’s content in shell script ? Current output: Desired output: Answer Use eval: