Apr 3, 2012 · What does a dollar sign followed by an at-sign (@) mean in a shell script? For example: umbrella_corp_options $@

$(command) is “command substitution”. As you seem to understand, it runs the command, captures its output, and inserts that into the command line that contains the $(…); e.g., $ ls -ld $(date +%B).txt -rwxr-xr-x 1 Noob Noob 867 Jul 2 11:09 July.txt ${parameter} is “parameter substitution”. A lot of information can be found in the shell’s man page, bash (1), under the “ …

Shell equality operators (=, ==, -eq) Asked 11 years, 7 months ago Modified 3 years, 2 months ago Viewed 635k times

Dec 14, 2024 · Shell - "Shell" is a program, which facilitates the interaction between the user and the operating system (kernel). There are many shell implementations available, like sh, Bash, C shell, Z shell, etc.

Nov 15, 2010 · A bashism is a shell feature which is only supported in bash and certain other more advanced shells. It will not work under busybox sh or dash (which is /bin/sh on a lot of distros), or certain other shells like the /bin/sh provided on FreeBSD.

Apr 7, 2017 · 116 Let's say I have .env file contains lines like below: USERNAME=ABC PASSWORD=PASS Unlike the normal ones have export prefix so I cannot source the file directly. What's the easiest way to create a shell script that loads content from .env file and set them as environment variables?

Sep 30, 2010 · How to represent multiple conditions in a shell if statement? Asked 14 years, 10 months ago Modified 3 years, 6 months ago Viewed 1.2m times

Mar 29, 2016 · 701 set -x enables a shell mode where all executed commands are printed to the terminal. In your case it's used for debugging, which is a typical use case for set -x: printing every command as it is executed may help you visualize the script's control flow if it is not functioning as expected. set +x disables it.

Aug 30, 2010 · How do I know if a variable is set in Bash? For example, how do I check if the user gave the first parameter to a function? function a { # if $1 is set ? }

Sep 14, 2012 · $! is the PID of the most recent background command. $0 is the name of the shell or shell script. Most of the above can be found under Special Parameters in the Bash Reference Manual. Here are all the environment variables set by the shell. For a comprehensive index, please see the Reference Manual Variable Index.