How to Get the Process ID (PID) in Go Go provides a simple way to access the current process ID. The Code import “os” pid := os.Getpid() Go in 2026 In 2026, Go 1.26+ is the standard. The os package provides Getpid() for the current process and Getppid() for the parent process. In cloud-native applications…
How to Get the Process ID (PID) in C/C++ Every running process has a unique PID assigned by the operating system. The Code #include <unistd.h> pid_t pid = getpid(); C/C++ in 2026 In 2026, getpid() is still the standard POSIX call. In C++20/23, while there isn’t a standard library function for PIDs yet, most developers…
How to Get the Parent Process ID (PPID) in Bash In Bash, every process has a parent. Knowing the PPID is useful for process management and debugging. The Command Simply use the built-in variable: echo $PPID Bash in 2026 While $PPID is still the standard, modern shell scripting often involves process substitution or background jobs….
How to debug a Bash script if it has some bugs? Common techniques like printing varibles out for checking apply for bash too. For bash, I also use 2 bash-specific techniques. Use errexit option Run the script with -e option like bash -e your-script.sh or add set -o errexit to the beginning of the script….
How to Get the Current Process ID (PID) in Bash The PID is a unique identifier for every running process. In Bash, you can get it easily. The Command Use the built-in variable: echo $$ Bash in 2026 For more advanced process management, you might use $BASHPID, which is slightly different from $$ in subshells….
How to get the running process’ pid in Python? In Python, you can get the pid of the current process by import os os.getpid() From the official doc: os.getpid() Return the current process id. One example os using os.getpid() to get process own ID: $ python3 Python 3.8.10 (default, Jun 22 2022, 20:18:18) [GCC 9.4.0]…
How to get all the keys of an associative array in Bash? There are at least 2 ways to get the keys from an associative array of Bash. Let’s start with an example associative array: $ declare -A aa $ aa[“foo”]=bar $ aa[“a b”]=c We can use the @ special index to get all the…
How to get the one character’s next character in ASCII table in Bash? For example, if I have ‘a’ in variable i, how to get ‘b’? First, we need to get the integer value for the character. char=’b’ charint=$(printf “%d” “‘$char'”) Then, we increase the integer by one let charint=$charint+1 Last, we can get the…
How to delete or get the number in the tail from a string in shell script (bash script)? Okay to call other tools. For example, from “/dev/sda8”, I want to get “/dev/sda” and “8” separately. This can be achieved by using sed as follows. To get the string after deleting the tailing numbers, we can…
How to split a string by string in Bash? For example, “a string separated by space” => [“a”, “string”, “separated”, “by”, “space”] and “a,string,separated,by,comma” => [“a”, “string”, “separated”, “by”, “comma”] You can convert a string to an array using the grammar like inarr=(${a}) If the delimiter is not space and delimiter is a single character…
Could you list the most important features or aspects for the C++ programming languages that describe its most important features/domains that are different from the others? For C++, as in Going Native 2012 Keynote by Bjarne Stroustrup: light-weight abstraction Key strengths: infrastructure software resource-constrained applications
In C++, what’s the standard or common data structure for a list of objects? In C++, the common data structure for a sequence (“list”) of objects may be std::vector. A vector is a dynamically resizable array. It is “The most extensively used container in the C++ Standard Library …, offering a combination of dynamic memory…
In C, what’s the standard or common data structure for a list of objects? In C, one common way to store a list/collection of objects of the same type is to use one-dimensional arrays. In C, an array is a collection of data objects of the same type. An array is in a contiguous memory…
In C, how to get the hostname of the node? In C, you may use the gethostname function. #include <unistd.h> int gethostname(char *name, size_t namelen); The gethostname() function shall return the standard host name for the current machine. The namelen argument shall specify the size of the array pointed to by the name argument. The…
In C++, how to get the hostname of the node? In C++, the C way works too. However, with Boost, you can use the boost::asio::ip::host_name() function to get the hostname as a std::string: namespace boost { namespace asio { namespace ip { /// Get the current host name. BOOST_ASIO_DECL std::string host_name(); … More at http://www.boost.org/doc/libs/1_63_0/boost/asio/ip/host_name.hpp…
In Go lang, how to get the hostname of the node? In Go, you can use the os.Hostname() function to get the hostname of the node. func Hostname() (name string, err error) Hostname returns the host name reported by the kernel. One example is as follows. The main.go source code: package main import ( “fmt”…
In Python, how to get the hostname of the node? In Python, you can get the hostname by the socket.gethostname() library function in the socket module: import socket hostname = socket.gethostname() Example: $ python Python 2.7.5 (default, Nov 6 2016, 00:28:07) [GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux2 Type “help”, “copyright”, “credits” or “license”…
In C, how to get the epoch timestamp, the number of seconds passed since the epoch? In C, from man 7 time: UNIX systems represent time in seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC). A program can determine the calendar time using gettimeofday(2), which returns time (in seconds and microseconds) that have elapsed since…
In C++, how to process a file line by line? The file is a plain text line like input.txt. As an example, the process can be to just print it out. In C++, you may open a input stream on the file and use the std::getline() function from the <string> to read content line by…
Any good suggestions on a Java REPL implementation like ‘scala’ and ‘python’ or ‘php -a’? The java-repl tool https://github.com/albertlatacz/java-repl/ works nicely for most situations for me. It is released as a .jar. Hence, it is easy to download and run: $ wget –quiet https://github.com/albertlatacz/java-repl/releases/download/428/javarepl-428.jar -O /tmp/javarepo-428.jar && java -jar /tmp/javarepo-428.jar One usage example is as…