Contents
How to select lines from a text file?
I use a lot of grep awk sort in my unix shell to work with medium-sized (around 10M-100M lines) tab-separated column text files. In this respect unix shell is my spreadsheet. But I have one huge problem, that is selecting records given a list of IDs.
How to get the first line of a file in Excel?
The “head -x” part of the command will get the first x lines of the files. It will then redirect this output to the tail command. The tail command will display all the lines starting from line number x. Quite obviously, if you take 13 lines from the top, the lines starting from number 13 to the end will be the 13th line.
How to display the number of lines in a file?
Use a combination of head and tail command in the following function the line number x: You can replace x with the line number you want to display. So, let’s say you want to display the 13th line of the file.
How does the head command get the lines of a file?
Explanation: You probably already know that the head command gets the lines of a file from the start while the tail command gets the lines from the end. The “head -x” part of the command will get the first x lines of the files. It will then redirect this output to the tail command.
How to find lines which are not present in another file?
By default, comm outputs 3 columns: left-only, right-only, both. The -1, -2 and -3 switches suppress these columns. So, -23 hides the right-only and both columns, showing the lines that appear only in the first (left) file.
How to find matching substrings in text file?
The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character.
Why are there false positives in non ID fields?
If your false positives are because an ID can be present in a non-ID field, loop through your file instead: The join utility is what you want. It does require the input files to be lexically sorted. The answers to this SO question helped me get around the niggles with join.