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Tag: unix

(Linux) Determine Percentage of Different Colors in Image

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

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: (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