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 $$ 21779 Start a python REPL and get its parent pid (the shell’s): $ python Python 2.7.5 (default, Nov 6…
How to get the running process’ parent process’ ID in Go? In Go, you may call the os.Getppid() func from the os package to get the parent process’ pid. func Getppid() int Getppid returns the process id of the caller’s parent. One example is as follows. $ gore gore version 0.2.6 :help for help gore>…
How to get the running process’ parent process’ ID in C / C++? In C and C++, you can call the getppid() library function which is a function from the POSIX library. #include <sys/types.h> #include <unistd.h> pid_t getppid(void); getppid() returns the process ID of the parent of the calling process. Example usage: getppid.c #include <stdio.h>…
How to get the running process’ pid in C / C++? In C and C++, you can call the getpid() library function which is a function from the POSIX library. #include <sys/types.h> #include <unistd.h> pid_t getpid(void); getppid() returns the process ID of the calling process. An example C program to get self process ID getpid.c:…
How to get the running process’ parent process’ ID in Bash? In Bash, you can get the parent process’s pid from the variable PPID. Note that in a (…) subshell, the $$ stores the subshell’s parent shell pid actually.
How to get the running process’ pid in Go lang? In Go, you may call the os.Getpid() func from the os package to get the parent process’ pid. func Getpid() int Getppid returns the process id of the caller. One example is as follows. $ gore gore version 0.2.6 :help for help gore> :import “fmt”…
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 running process’ pid in Bash? In Bash, you can get the process ID from the variable $$. Note that in a subshell invoked by ‘(…)‘, $$ is actually the parent process’ pid. In Bash 4, you can also use $BASHPID to get the process pid.
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]…
Question: how to find the disk where the Linux’s root(/) is on in Bash? The root may be on a LVM volume or on a raw disk. 2 cases: One example: # df -hT | grep /$ /dev/sda4 ext4 48G 32G 14G 71% / For another example: # df -hT | grep /$ /dev/mapper/fedora-root ext4…
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…
In Zimbra server, how to set Zimbra web service’s hostname and port? Set Zimbra Web service’s host and port (to mail.domain.com:80 as an example) for a mail domain domain.com: zmprov md domain.com zimbraPublicServiceHostname mail.domain.com zmprov md domain.com zimbraPublicServicePort 80 Reference: https://wiki.zimbra.com/wiki/When_using_a_proxy,_the_’change_password’_box_doesn’t_load
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 get the version of Zimbra I am using in a Zimbra server? In Zimbra, to get the version of Zimbra you are using, you can call zmcontrol -v: $ zmcontrol -v Release 7.2.6_GA_2926.F13_64_20131203115902 F13_64 FOSS edition.
How to disable the DHCP service in dnsmasq on Linux? That is, to leave only dnsmasq’s DNS service. The `/etc/dnsmasq.conf` file may have lines that enable DHCP service of dnsmasq. By default, the DHCP is disabled in dnsmasq (check one example dnsmasq.conf file). To disable DHCP service in dnsmasq, in `/etc/dnsmasq.conf`, remove or disable 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…