Feb 20, 2011 · $0-The filename of the current script. $#-The number of arguments supplied to a script. $$-The process number of the current shell. For shell scripts, this is the process ID under which they are executing.

To extend terdon's answer, I found that Unix / Linux - Shell Basic Operators on Tutorials Point also includes file-related operators (as well as other useful ones).-b file Checks if file is a block special file; if yes, then the condition becomes true.

See What is the difference between > and >> (especially as it relates to use with the cat program)?, What does “3>&1 1>&2 2>&3” do in a script? and of course, your shell's manual. (There are some further explanations in Is this a typo in Bash manual's redirection section? too.) –

Feb 25, 2014 · That way, all commands within the script will be run with root privileges and you only need to give the password once when launching the script. If you need a particular command within the script to be run without sudo privileges, you can run it as a regular user with (thanks Lie Ryan): sudo -u username command

Mar 27, 2015 · @G-ManSays'ReinstateMonica': That's an excellent question, and, thinking about it, while it is true that read is consistent with Bash's input-parsing behavior for its own commands, I would say it is rather unusual for a programming language's equivalent read function to do line splicing; for example, C source code also supports backslash line continuations, but fread and …

Usually the parent shell guesses that the script is written for the the same shell (minimal Bourne-like shells run the script with /bin/sh, bash runs it as a bash subprocess) ... Because of this, when the script is executed, you won't find a process named after script (or a process with the script's name in the command line) and pgrep will fail.

Jan 22, 2014 · @RobBell bash a type of shell program used to interpret the bash script. Its synopsis is bash [options] [command_string | file], so it is possible we execute one command like this echo "echo hello world" | bash or bash script.sh, because we don't excute script with ./ so it is even no need to add #!/bin/bash(specify the interpreter) in the script .

I'm reading an example bash shell script: #!/bin/bash # This script makes a backup of my home directory. cd /home # This creates the archive tar cf /var/tmp/home_franky.tar franky > /dev/null 2>&1 # First remove the old bzip2 file. Redirect errors because this generates some if the archive # does not exist.

May 25, 2012 · On Linux and other Unix-like systems you have a choice of multiple shells. The shell is responsible not only for presenting an interactive environment where it shows a prompt, but it also interprets your commands whether they are typed or loaded from a script. bash is the most common shell used as a default shell for users of Linux systems. It ...

The question doesn't mention bash, and in fact deliberately only mentions shell script, both in the tags, and in the question. This answer would fail in a POSIX environment. This answer would fail in a POSIX environment.