mapfile -tn 0 lines < "$1" printf '%s\n' "${#lines[@]}" } 示例函数(bash 3): 此方法使用的内存少于mapfile方法,并在bash3中工作,但对于较大的文件,它的速度较慢。 lines_loop() { # Usage: lines_loop "file" count=0 while IFS= read -r _; do ((count++)) done < "$1" printf...
mapfile -tn 0 lines < "$1" printf '%s\n' "${#lines[@]}" } 1. 2. 3. 4. 5. 示例函数(bash 3): 此方法使用的内存少于mapfile方法,并在bash3中工作,但对于较大的文件,它的速度较慢。 lines_loop() { # Usage: lines_loop "file" count=0 while IFS= read -r _; do ((count++))...
How to create an infinite loop in bash? How to find if a number is odd or even in bash? How to iterate over a bash array? How to loop over each line of a file? How to iterate over a list of files? How to use numbers with leading zeros in a bash loop? How to iterate over ...
Theread -rcommand reads the file and stores the strings to thelinevariable. Next, theecho $linedisplays the lines to the standard output. Lastly, thefilenamevariable is given as an input to the while loop. In the following example, I am giving thescript.shas the file name to read. Ba...
Terminate until loop based on user input Using nested while loops Using until loop to sleep/wait for background task started in script Using while loop to read pid from ps output that is not terminated Searching any string in a file using loop and exit ...
In the script, thecatcommand is executed using command substitution. The output ofcat file1.txtreplaces the command, and theforloop iterates through the command’s output and prints it to the standard output using theprintfcommand. #!/bin/bashprintf"Program prints the lines of a file\n\n...
/bin/bashif[ ! -d $1];thenecho"The file you input is not a directory,exit!"exit1fideclare-i textCount=0declare-i lineCount=0foriin$1/*; do if [ -f $i ]; then lines=$(wc -l $i | cut -d " " -f 1) textCount=$[$textCount+1]...
head() {# Usage: head "n" "file"mapfile-tn"$1"line <"$2"printf'%s\n'"${line[@]}"} 用法示例: $head2 ~/.bashrc# PromptPS1='➜ '$head1 ~/.bashrc# Prompt 获取文件的最后N行 替代tail命令。 CAVEAT:需要bash4+ 示例功能: ...
done < testfile Blank Line Not Ignored See the result, blank line is not ignored. Also, an interesting thing to note is how white spaces are trimmed by thereadcommand. A simple way to ignore blank lines when reading the file content is to use the test operator with the-zflag which che...
3. File line counter There are times when you have a file having thousands of lines but what if you want to count the number of the lines? You can use the while loop in that case: #!/bin/bash filename="example.txt" line_count=0 ...