What are the special dollar sign shell variables? - Stack Overflow
Sep 14, 2012 · In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &; echo $! will return the PID of the process …
bash - Shell equality operators (=, ==, -eq) - Stack Overflow
It depends on the Test Construct around the operator. Your options are double parentheses, double brackets, single brackets, or test. If you use ((…)), you are testing arithmetic equality …
What does the line "#!/bin/sh" mean in a UNIX shell script?
Sep 10, 2011 · When you try to execute a program in unix (one with the executable bit set), the operating system will look at the first few bytes of the file. These form the so-called "magic …
The UNIX® Standard | www.opengroup.org
May 22, 2025 · Single UNIX Specification- “The Standard” The Single UNIX Specification is the standard in which the core interfaces of a UNIX OS are measured. The UNIX standard …
unix - How to check permissions of a specific directory ... - Stack ...
I know that using ls -l "directory/directory/filename" tells me the permissions of a file. How do I do the same on a directory? I could obviously use ls -l on the directory higher in the hierarchy...
linux - How can I recursively find all files in current and subfolders ...
May 5, 2011 · How can I recursively find all files in current and subfolders based on wildcard matching?
Boolean operators ( &&, -a, ||, -o ) in Bash - Stack Overflow
Dec 8, 2013 · What is the difference between the &&, ||, -a, and -o Unix operators? What are the restrictions on the usage of both types? Is it simply that the && and || operators should be used ...
unix - how to find host name from IP with out login to the host
Oct 20, 2014 · i need to find the host name of a UNIX host whose IP is known with out login to that UNIX host
Setting environment variables in Linux using Bash
Mar 5, 2017 · Set a local and environment variable using Bash on Linux Check for a local or environment variables for a variable called LOL in Bash: $ set | grep LOL $ $ env | grep LOL $ …
How to redirect output to a file and stdout - Stack Overflow
Jun 19, 2014 · A note on terminology: when you execute foo > output the data is written to stdout and stdout is the file named output. That is, writing to the file is writing to stdout. You are …