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What is the best way (better performance) to read a specific line of a file? Currently, I'm using the following command line:
head -line_number file_name | tail -1
ps.: preferentially, using shell tools.
941
Method 1: Read a File Line by Line using readlines() readlines() is used to read all the lines at a single go and then return them as each line a string element in a list. This function can be used for small files, as it reads the whole file content to the memory, then split it into separate lines.
Solution 1 You can use fgets [^] in a loop to read a file line by line. When no more lines can be read, it will return NULL. On the first line you can use sscanf[^] to extract the integer.
Using the head and tail Commands Let's say we want to read line X. The idea is: First, we get line 1 to X using the head command: head -n X input. Then, we pipe the result from the first step to the tail command to get the last line: head -n X input | tail -1.
The readline method reads one line from the file and returns it as a string.
You could use sed.
# print line number 10
$ sed -n '10p' file_name
$ sed '10!d' file_name
$ sed '10q;d' file_name
ruby -ne '$.==10 and (print; exit)' file
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