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Full Discussion: Unix Shell Scripting
Top Forums UNIX for Dummies Questions & Answers Unix Shell Scripting Post 302686489 by Don Cragun on Tuesday 14th of August 2012 04:57:21 PM
Old 08-14-2012
First, there are two flavors of the echo utility. The BSD-based version of echo concatenates all of the operands it is given and write them to standard output followed by a <newline>. If the -n option is present it doesn't output the <newline>. I assume this is the version of echo you have on your system. (On the UNIX System V-based version of echo -n is not an option; it is just another operand to be printed. But there are several escape sequences in the string operands that the System V echo will translate ("\t" -> <tab>, "\n" -> <newline>, "\0" -> skip the remainder of this and any following operand and skip the normal trailing <newline>, etc.) that the BSD echo will not change.) If you want to output some text without the normal trailing <newline> in a way that will be portable to all UNIX and Linux systems, use the printf utility instead of echo.

So, your cout << "string" being roughly equivalent to [icode]echo -n "string" is pretty close. But echo $1 is also an output statement; not an input statement. I'm more of a C guy, than C++. In C it is roughly equivalent to printf("%s\n", argv[1]);. The equivalence is would be exact if you used "$1" instead of $1 because if the string isn't quoted and you have the default setting for $IFS, any sequences of one or more <space> and <tab> characters will be translated to a single space and passed to the echo command as individual operands instead of as a single string.

In the shells (bash, ksh, sh, ...), $n (1 <= n <= 9) refers to the 9th argument given to to the shell script when it was invoked. If you use ${n}, n can be greater than 9. $0 refers to the name of the script (like argv[0] in a C or C++ program). So, if you have a regular file with the execute bit set named "script" that contains something like:
Code:
#!/bin/ksh
echo -n "There once was a "
echo $1
echo -n "that "
echo $2
echo -n "who liked to " 
echo $3
echo -n "There once was a " $1 " that " $2 " who liked to " $3

and invoked it as:
Code:
script man "spent a lot of time in a swimming pool" "win gold medals!"

the output should be something like:
Code:
There once was a man
 that spent a lot of time in a swimming pool
 who liked to win gold medals!
There once was a man that spent a lot of time in a swimming pool who liked to win gold medals!

 

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qwtinstall(3)							 Qwt User's Guide						     qwtinstall(3)

NAME
qwtinstall - .TH "qwtinstall" 3 "Mon Aug 1 2011" "Version 5.2.2" "Qwt User's Guide" NAME
qwtinstall - .PP Introduction ============ Qwt uses qmake to build all its components and examples. qmake is part of a Qt distribution. qmake reads project files, that contain the options and rules how to build a certain project. A project file ends with the suffix '*.pro'. Files that end with the suffix '*.pri' are included by the project files and contain definitions, that are common for several project files. qwtconfig.pri is read by all project files of the Qwt package. So the first step is to edit qwtconfig.pri to adjust it to your needs. MathML Extension ================ Qwt/Qt4 supports the MathML render engine from the Qt solutions package, that is only available with a commercial Qt license. You need a release of qtmmlwidget >= 2.1. Copy the files qtmmlwidget.[cpp|h] to textengines/mathml. Documentation ========================== Qwt includes a class documentation, that is available in various formats: - Html files - PDF document - Qt Compressed Help (*.qch ) for the Qt assistant or creator. You can load it 'Edit Preferences' -> 'Documentation' -> 'Add...' - Man pages ( UNIX only ) A) Unix Qt3/Qt4 ========================== qmake make make install If you have installed a shared library it's path has to be known to the run-time linker of your operating system. On Linux systems read the LD_LIBRARY_PATH (on some systems LIBPATH is used instead, on MacOSX it is called DYLD_LIBRARY_PATH) environment variable. If you only want to check the Qwt examples without installing something, you can set the LD_LIBRARY_PATH to the lib directory of your local build. If you didn't enable autobuilding of the examples in qwtconfig.pri you have to build the examples this way: cd examples qmake make B) Win32/MSVC Qt3/Qt4 ===================== Please read the qmake documentation how to convert your *.pro files into your development environment. F.e MSVC with nmake: qmake qwt.pro nmake If you didn't enable autobuilding of the examples in qwtconfig.pri you have to build the examples this way: cd examples qmake examples.pro nmake admin/msvc-qmake.bat helps users of Visual Studio users to generate makefiles or project files (.dsp for MSVC-6.0 or vcproj for MSVC.NET) for Qwt. To generate makefiles, type: 'adminvc-qmake' To generate project files, type: 'adminvc-qmake vc' When you have built a Qwt DLL you need to add the following define to your compiler flags: QWT_DLL. Windows doesn't like mixing of debug and release binaries. Most of the problems with using the Qwt designer plugin are because of trying to load a Qwt debug library into a designer release executable. C) Win32/MinGW Qt4 ================== C1) Windows Shell Start a Windows Shell, where Qt4 is initialized. ( F.e. with qmake qwt.pro make If you didn't enable autobuilding of the examples in qwtconfig.pri you have to build the examples this way: cd examples qmake examples.pro make make install C2) MSYS Shell Qt >= 4.3.0 Support for the MSYS Shell has been improved in Qt 4.3.0. Now building Qwt from the MSYS Shell works exactly like in UNIX or in the Windows Shell - or at least it should: because of a bug in Qt 4.3.0 you always have to do a 'qmake -r'. C3) MSYS Shell Qt < 4.3.0 For Qt < 4.3.0 you have to set the MINGW_IN_SHELL variable. make will run into errors with the subdirs target, that can be ignored (make -i). export MINGW_IN_SHELL=1; qmake make -i make -i install If you didn't enable autobuilding of the examples in qwtconfig.pri you have to build the examples this way: cd examples qmake examples.pro make -i make -i install C1-C3) When you have built a Qwt DLL you need to add QWT_DLL to your compiler flags. If you are using qmake for your own builds this done by adding the following line to your profile: 'DEFINES += QWT_DLL'. Windows doesn't like mixing of debug and release binaries. Most of the problems with using the Qwt designer plugin are because of trying to load a Qwt debug library into a designer release executable. D) MacOSX Well, the Mac is only another Unix system. So read the instructions in A). In the recent Qt4 releases the default target of qmake is to generate XCode project files instead of makefiles. So you might need to do the following: qmake -spec macx-g++ D) Qtopia Core I only tested Qwt with Qtopia Core in qvfb (Virtual Framebuffer Devivce) Emulator on my Linux box. To build Qwt for the emulator was as simple as for a regular Unix build. qmake make E) Qtopia (!= Qtopia Core) I once compiled the Qwt library against Qtopia 4.2.0 successfully - but not more. It should be possible to build and install Qwt, but it's not done yet. Good luck ! Version 5.2.2 Mon Aug 1 2011 qwtinstall(3)
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