2020. 2. 13. 18:52ㆍ카테고리 없음
There is a directory in System/Library for startup items I presume: StartupItems I need to have a shell script that will configure ethernet interface at start up, with local network address and subnet mask. I need to do this because the network preferences for configuring the ethernet interface will NOT set it using manual settings. THIS appears to be a serious bug, or my installation is bad. I was given the advice to use networksetup from the command line but that will not configure the ethernet interface in such a way that the configurations will be there on reboot. The script needs to do its work with root privileges, or with sudo, but I am assuming that if it uses sudo, there will be a password dialog presented at boot time when the boot process gets to that script. (I have had enough experience with FreeBsd and Linux to find my way around in the terminal, but not necessarily as it applies to Mac OSX).
Jul 30, 2010 - The ability to create and make your own custom bash scripts is on of the biggest advantages to working off a unix based operating system (like.
One way of doing it would be assigning the script a launchd service: Create the shell script as usual. Then you can make a launchd service to run it at startup. Those are located at /Library/LaunchDaemons. These are in the XML property list format.
Create another and populate it with something like this:
. @annually (same as @yearly) @monthly Run once a month, '0 0 1.' .
@weekly Run once a week, '0 0. 0'. @daily Run once a day, '0 0.' .
@midnight (same as @daily) @hourly Run once an hour, '0.' .
To run a non-executable sh script, use: sh myscript To run a non-executable bash script, use: bash myscript To start an executable (which is any file with executable permission); you just specify it by its path: /foo/bar /bin/bar./bar To make a script executable, give it the necessary permission: chmod +x bar./bar When a file is executable, the kernel is responsible for figuring out how to execte it. For non-binaries, this is done by looking at the first line of the file.
It should contain a hashbang: #! /usr/bin/env bash The hashbang tells the kernel what program to run (in this case the command /usr/bin/env is ran with the argument bash). Then, the script is passed to the program (as second argument) along with all the arguments you gave the script as subsequent arguments.
That means every script that is executable should have a hashbang. If it doesn't, you're not telling the kernel what it is, and therefore the kernel doesn't know what program to use to interprete it. It could be bash, perl, python, sh, or something else.
(In reality, the kernel will often use the user's default shell to interprete the file, which is very dangerous because it might not be the right interpreter at all or it might be able to parse some of it but with subtle behavioural differences such as is the case between sh and bash). A note on /usr/bin/env Most commonly, you'll see hash bangs like so: #!/bin/bash The result is that the kernel will run the program /bin/bash to interpret the script. Unfortunately, bash is not always shipped by default, and it is not always available in /bin. While on Linux machines it usually is, there are a range of other POSIX machines where bash ships in various locations, such as /usr/xpg/bin/bash or /usr/local/bin/bash. To write a portable bash script, we can therefore not rely on hard-coding the location of the bash program. POSIX already has a mechanism for dealing with that: PATH.
Writing Shell Scripts In Linux
The idea is that you install your programs in one of the directories that are in PATH and the system should be able to find your program when you want to run it by name. Sadly, you cannot just do this: #!bash The kernel won't (some might) do a PATH search for you. There is a program that can do a PATH search for you, though, it's called env. Luckily, nearly all systems have an env program installed in /usr/bin. So we start env using a hardcoded path, which then does a PATH search for bash and runs it so that it can interpret your script: #!/usr/bin/env bash This approach has one downside: According to POSIX, the hashbang can have one argument.
In this case, we use bash as the argument to the env program. That means we have no space left to pass arguments to bash. So there's no way to convert something like #!/bin/bash -exu to this scheme. You'll have to put set -exu after the hashbang instead. This approach also has another advantage: Some systems may ship with a /bin/bash, but the user may not like it, may find it's buggy or outdated, and may have installed his own bash somewhere else.
This is often the case on OS X (Macs) where Apple ships an outdated /bin/bash and users install an up-to-date /usr/local/bin/bash using something like Homebrew. When you use the env approach which does a PATH search, you take the user's preference into account and use his preferred bash over the one his system shipped with.