I'm developing a little command-line tool for a friend. I'm on linux, but he's on Windows and I want to make the compilation process easy for him, as he's not used to having to compile stuff himself.
Building the tool works flawlessly, but now I want to add an 'install' target to the Makefile that copies the binary to his cygwin64/bin folder, which is (supposed to be) on his path. However, I want the Makefile to still run under linux. Is there a generic approach to his? Or should I grep, sed, cut and awk my way through the PATH string and extract the folder I'm looking for?
Related
I am trying to do a directory-wide search for specific strings in JSON files. The only problem is that these JSON files are only one line, so when I cat all of them, all strings occur a magical "1" time...since there's only one line even when I string them all together.
An easy solution, which I see a lot (here and here), is grep -o. Only problem is it doesn't come standard on my Gitbash. I solved my immediate problem by just installing the latest Cygwin. However, I'm wondering if there was an easier/more granular solution. Is it possible to do the equivalent of "apt-get install" or similar on Gitbash? Or can someone explain to me a quick-and-dirty way to extract and install the tar file in Gitbash?
The other approach is to:
use a cmd session (using the git-cmd.bat which packaged with Git for Windows)
use the grep included Gnu for Windows, which supports the -o option (and actually allow you to use most of the other Unix commands that your script might be currently using)
After somewhere searching finally not getting what i want.
I am working on some embedded board with linux system. And many users access it by telnet.So each user suppose copy some binary somewhere and executed like ./binary.So i can see this process running by simply ps command but from where it's running i don't know.
somewhere found that, use which command but as per my understanding(if i am not wrong) which command find only path of that binary whether it's currently executing or not.
And what if multiple users copied same binary in different path?
Also looked another solution use readlink but limited busybox binary supported in my target board. So readlink is not there.
One another solution like
file /proc/"proess id"/exe but here file command not present because of custome linux in my board which contain only limited functionality and binary.
So any other solution is there?
Try ls -l /proc/"proess id"/exe. ls utility from GNU coreutils shows links with -l option, but I don't have exact information about ls from busybox.
I am trying to do this:
I want to call a make (Makefile exists in some other directory, abc path can be used) from a shell script located in a different directory. How do I do this?
Since shell scripting does not allow me to cd into the Makefile directory and execute make, how can I write the shell command (by giving path to the Makefile to be executed) to execute make?
GNU make accepts many options, notably -C to change directory before running, and -f for giving the Makefile to follow.
Combine them appropriately.
Consider using remake to ease debugging (notably with -x) of Makefile related issues. With GNU make version 4 or better, also use make --trace...
You could have your own executable shell script (e.g. in your $HOME/bin/ which would be in your $PATH) which uses both cd and make).
You could consider other build automation tools (ninja perhaps)
Read also P.Miller's paper Recursive Make considered harmful
Is there any efficient way (maybe by abusing the gcc preprocessor?) to get a set of stripped kernel sources where all code not needed according to .config is left out?
Well got some steps into a solution.
First, one can obtain the used compiler commands by
make KBUILD_VERBOSE=1 | tee build.log
grep '^ gcc' build.log
For now, I select only one gcc command line for further steps. For example the build of kernel/kmod.c, it looks like:
gcc <LIST OF MANY OPTIONS> -c -o kernel/kmod.o kernel/kmod.c
I now remove the option -c, -o ... and add -E, thus disabling compilation and writing preprocessor output to the screen. Further I add -fdirectives-only to prevent macro expansion and -undef to remove the GNU defined macro definitions. -nostdinc to remove the standard c headers is already added by the kernel makefile.
Now includes are still included and thus expanded on the preprocessor output. Thus I pipe the input file through grep removing them: grep -v '#include' kernel/kmod.c. Now only one include is left: autoconf.h is included by the Makefile's command line. This is great as it actually defines the macros used by #ifdef CONFIG_... to select the active kernel code.
The only thing left is to filter out the preprocessor comments and the remaining #defines from autoconf.h by means of grep -v '^#'.
The whole pipe looks like:
grep -v '#include' kernel/kmod.c | gcc -E -fdirectives-only -undef <ORIGINAL KERNEL BUILD GCC OPTIONS WITHOUT -c AND -o ...> - |grep -v '^#'
and the result is a filtered version of kernel/kmod.c containing the code that is actually build into kmod.o.
Questions remain: How to do that for the whole source tree? Are there files that are actually build but never used and stripped at linking?
Kernel Minimization Script :
A project inspired by this question and providing an easy answer...
It contains a Python script that generate a minimized sources code during build time. The new minimized source tree will only contain used sources. (project page)
Info :
The script is tested working with the kernel v4.14.x, however building the kernel one more time from those generated minimized sources require to copy make files and Kconfig files etc... at least we could easily isolate only used source for investigations and development
Usage :
cd /kernel/sources
make
wget https://github.com/Hitachi-India-Pvt-Ltd-RD/minimization/raw/master/minimize.py
export PATH=$PATH:`pwd`
make C=2 CHECK=minimize.py CF="-mindir ../path-to-minimized-source-tree/"
Note & Reminder :
If we are building within and against the targeted machine, we also have the make localmodconfig command that shrink the current config file with only the currently used modules, if used before "Minimization" it will generate further more stripped sources
Compile everything and use atime to find out which files were not used. It might not be very accurate but it's probably worth a try.
I'm pretty new to programming for Linux environments, so I don't exactly know what to search for in order to answer this question for myself. I need to understand how applications set the shell to accept a certain command to start them. For example, you can start Firefox from the command line by executing the command: firefox.
I don't know where this is defined. Makefile? Configure script? In the source code itself?
Any resources / reading on Linux programming tidbits like these would be greatly appreciated!
Thank you.
Firefox is launched by the command "firefox" because there is an executable file in one of the folders in the $PATH environment variable called "firefox".
Are you talking about the PATH variable? It seems like you are.
In linux, you should be able to type: "echo $PATH" (without quotes) and get a ":"-separated list of locations where programs are located (like firefox).
If you need to add something to your path, you should be able to do:
export PATH=$PATH:/another/directory
In your shell (which is most likely bash)
You can also type:
which firefox
To display the location of the firefox executable.
Typically the shell is going to have an environment variable called $PATH set. This is just an ordered list of all the directories to look when somebody types in a command. As soon as it finds an executable file (by which I mean a file for which you have execute permissions, not a file ending in .exe) with the same name as whatever was typed, it will run that file. Common directories in $PATH might be /bin, /usr/local/bin, ~/bin, etc.
So, when you type 'firefox', the shell looks through all the directories in $PATH until it finds /usr/local/bin/firefox, which it then runs. To make your own programs run the same way, you'll either need to put them (or a symbolic link to them) in a directory that is likely to be in every user's path (/usr/local/bin/ is a good choice), or you'll need to get your users to add your program's directory to their $PATH.
For a more complete description, see the Wikipedia article about the $PATH variable.
As an alternative to the modification of $PATH mentioned earlier, you could also copy or link your executable in one of the directories already in your $PATH. more specifically, /usr/local/bin/ is available on most UNIX system for pretty much this purpose (installing software outside the default package management of the operating system).
It has to be in the path as everyone else mentioned, but you might also need to make it executable with something like this:
chmod +x /path/to/file
And if it's a script there's usually a shebang at the top that tells the os what to use to execute it:
#! /usr/bin/python
Often, large packages are installed in /opt with a wrapper script or link somewhere in the PATH. For example, on my system, Google Picasa is installed in /opt/google/picasa and there is a symlink at /usr/bin/picasa to /opt/google/picasa/3.0/picasa
Firefox is at /usr/bin/firefox on my system and that's a symlink to /usr/bin/firefox-3.0 which is itself a symlink to /usr/lib/firefox-3.0.11/firefox.sh - That shell file fumbles around until it finally runs /usr/lib/firefox-3.0.11/firefox (unless it finds a reason to do something else). That, finally, is a binary executable. So /usr/lib is where firefox is installed, for me.
You can use this command to find out where a program is:
type -a firefox
Then, you can find out what kind of file it is using this:
file /usr/bin/firefox
Also see the Filesystem Heirarchy Standard for more information about recommended locations for files and programs.