Editing 1654: Universal Install Script
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The <code>install.sh</code> file provided in the comic is a {{w|shell script}}, which attempts to fix this problem by acting as a "universal install script" that contains a lot of common install commands used in various Unix-like systems. This script in particular is interpreted by the {{w|Bourne Again Shell}} (Bash), which is denoted by the <code>#!/bin/bash</code> in the first line. In between each of the install commands in the script is the & character, which in {{w|POSIX}}-compatible {{w|Unix shell|shells}} (including {{w|Bash (Unix shell)|Bash}}, a popular shell scripting language) means it should continue to run the next command without waiting for the first command to finish, also known as "running in the background". This has the effect of running all the install commands simultaneously; all output and error text provided by them will be mixed together as they are all displaying on the screen around the same time. | The <code>install.sh</code> file provided in the comic is a {{w|shell script}}, which attempts to fix this problem by acting as a "universal install script" that contains a lot of common install commands used in various Unix-like systems. This script in particular is interpreted by the {{w|Bourne Again Shell}} (Bash), which is denoted by the <code>#!/bin/bash</code> in the first line. In between each of the install commands in the script is the & character, which in {{w|POSIX}}-compatible {{w|Unix shell|shells}} (including {{w|Bash (Unix shell)|Bash}}, a popular shell scripting language) means it should continue to run the next command without waiting for the first command to finish, also known as "running in the background". This has the effect of running all the install commands simultaneously; all output and error text provided by them will be mixed together as they are all displaying on the screen around the same time. | ||
| β | The script accepts the name of a program or package as an argument when you run it. This value is then referenced as "$1" (argument number 1). Everywhere the script says "$1", it substitutes in the name of the package you gave it. The end result is the name being tried against a large number of software repositories and package managers, and | + | The script accepts the name of a program or package as an argument when you run it. This value is then referenced as "$1" (argument number 1). Everywhere the script says "$1", it substitutes in the name of the package you gave it. The end result is the name being tried against a large number of software repositories and package managers, and hopefully, at least one of them will be appropriate and the program will be successfully installed. Near the end, it even tries copying the source code from an online source and then runs several commands which compile/build the program. |
All in all, this script would probably work; it runs many standard popular repository programs and package managers, and runs the nearly-universal commands needed to build a program. Most of the commands would simply give an error and exit, but hopefully the correct one will proceed with the install. | All in all, this script would probably work; it runs many standard popular repository programs and package managers, and runs the nearly-universal commands needed to build a program. Most of the commands would simply give an error and exit, but hopefully the correct one will proceed with the install. | ||
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The title text mentions the possibility that the same program may be in multiple repositories. In this case, the script may download and install several different versions of the same software. This would likely only create a confusing install-base, as an operating system would tend to prefer to use one version over another regardless of which one functions. It is unlikely that different repositories include the same software, with the exception of pip/easy_install and the two forms of apt-get, which would each likely see the software is already installed and abort. | The title text mentions the possibility that the same program may be in multiple repositories. In this case, the script may download and install several different versions of the same software. This would likely only create a confusing install-base, as an operating system would tend to prefer to use one version over another regardless of which one functions. It is unlikely that different repositories include the same software, with the exception of pip/easy_install and the two forms of apt-get, which would each likely see the software is already installed and abort. | ||
| β | The title text also mentions that adding a way of automatically saying "yes" to questions asked during the different repository-fetching programs' running, by making them read input from another program that writes a (nearly) endless stream of "y"s, could simplify things further. This would not work for any | + | The title text also mentions that adding a way of automatically saying "yes" to questions asked during the different repository-fetching programs' running, by making them read input from another program that writes a (nearly) endless stream of "y"s, could simplify things further. This would not work for any curses-based menus, or to answer any more complicated questions. Adding <code>2>/dev/null</code> to a command redirects the second output stream (the "error stream") to the null device driver, which discards all writes to it, meaning errors (the package not existing) will not be sent to the screen. |
==Transcript== | ==Transcript== | ||
