How to convert a piece of HTML code to plain text without leading and ending spaces in PHP? For example, I would like to convert <div> <b>hello</b> world</div> to a string hello world You may use this piece of code in PHP to strip HTML tags, remove leading and ending spaces and convert special characters…
How to get the full request URL of the page being processed in PHP? If you are sure the request is a http or https one, and the PHP script is executed according to (e.g. by a load balancer or apache reverse proxy) the REQUEST_URI/HTTP_HOST which are set by the client, the PHP script can…
How to print all fields after a certain field with awk on Linux? Say, I want to print out all fields after field $3: a b c d e f a b b b a a c d should be transformed to d e f b d You may use a for loop in awk…
How to send a POST request in Go? For example, send a POST of content like ‘id=8’ to a URL like https://example.com/api. In Go, the http package provides many common functions for GET/POST. Related to POST requests, the package provides 2 APIs: Post Post issues a POST to the specified URL. func (c *Client) Post(url,…
How to add a prefix string at the beginning of each line in Bash shell script on Linux? For example, assume we have a file a.txt: line 1 line 2 I want to have, pre line 1 pre line 2 You may use sed, the stream editor for filtering and transforming text: sed -e ‘s/^/pre…
How to detect whether a file is being written by any other process in Linux? Before a program open a file to processes it, it wants to ensure no other processes are writing to it. Here, we are sure after the files are written and closed, they will not be written any more. Hence, one-time…
How to count the number of reads in each chromosome in a bam file? The bam file is already sorted by the chromosome names. If the bam file is indexed, you may quickly get these info from the index: samtools idxstats in.bam | awk ‘{print $1″ “$3}’ If the bam file is not indexed, you…
In Linux, how to kill a process and all its child processes? For example, a Bash script A starts B, B starts C and C calls rsync. I would like to kill A and all its child processes all together. How to do this? There are possibly many answers to this question. One of the…
How to get the mtime of a file on Linux from the file’s path? You can use stat to get the file status including the mtime: %y time of last modification, human-readable %Y time of last modification, seconds since Epoch As an example, $ stat -c %y ./file 2017-06-26 13:33:06.764042064 +0800 $ stat -c %Y…
In C++, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In C++, you may print the string and then ‘n’ or std::endl to STDOUT by operating on the std::cout stream: std::cout << your_string << std::endl;…
In OCaml, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In OCaml, you may print a string with the end line character to STDOUT using the function in the Pervasives module: val print_endline : string…
In Perl, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In Perl, to nicely print a new line to STDOUT, you can use the “say” feature which “Just like print, but implicitly appends a newline”:…
In Java, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In Java, you can print string in a new line by ‘System.out.println()’ to STDOUT: System.out.println(“my msg here”); In Java, print a string str to STDERR…
In C, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In C, to print to STDOUT, you may do this: printf(“%sn”, your_str); For example, $ cat t.c #include <stdio.h> void main() { printf(“%sn”, “hello world!”);…
In PHP, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In PHP, you may print a line to STDOUT using echo by appending the PHP_EOL to the string: echo $your_msg . PHP_EOL; For example, $…
In Bash, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In Bash, you can simply use the echo command: echo “your message here” or echo your message here Examples: $ echo the message here the…
In Python, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In Python, to print a string str with a new line to STDOUT: print str In Python to print a line to STDERR: import sys…
In Go, how to print a string as a line to STDOUT? That is, the string and the newline character, nicely? And similarly, how to print the line to STDERR? In Go, you can use the ‘Println()’ func from the ‘fmt’ package to print a line to STDOUT: import(“fmt”) fmt.Println(“my msg here”) In Go, os.Stderr…
How to get the running process’ parent process’ ID in Python? In Python, you can get the parent process’ pid by calling os.getppid(): import os ppid = os.getppid() One example: The shell’s pid: $ echo $$ 21779 Start a python REPL and get its parent pid (the shell’s): $ python Python 2.7.5 (default, Nov 6…
How to get the running process’ parent process’ ID in Go? In Go, you may call the os.Getppid() func from the os package to get the parent process’ pid. func Getppid() int Getppid returns the process id of the caller’s parent. One example is as follows. $ gore gore version 0.2.6 :help for help gore>…