I want to ask how to remove path in cygwin. Let's say I have 3 paths:
PATH=path1:path2:path3
I want to remove path2 so it will be:
PATH=path1:path3
But actually i have a lot of path inside and it will painful to rewrite it manually. Any suggestion?
A simple solution is to use the bash or csh command-line:
export PATH=`echo $PATH | sed s/:path2//`
But this will only work 99.9% of the time. To handle the edge cases, such as when path2 is at the start, or when it is part of another path, you'll need:
export PATH=`echo $PATH | sed "s/:path2:/:/g;s/^path2://;s/:path2$//"`
Related
Dipping my toes into Bash coding for the first time (not the most experienced person with Linux either) and I'm trying to read the version from the version.php inside a container at:
/config/www/nextcloud/version.php
To do so, I run:
docker exec -it 1c8c05daba19 grep -eo "(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?" /config/www/nextcloud/version.php
This uses a semantic versioning RegEx pattern (I know, a bit overkill, but it works for now) to read and extract the version from the line:
$OC_VersionString = '20.0.1';
However, when I run the command it tells me No such file or directory, (I've confirmed it does exist at that path inside the container) and then proceeds to spit out the entire contents of the file it just said doesn't exist?
grep: (0|[1-9]\d*).(0|[1-9]\d*).(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-])(?:.(?:0|[1-9]\d|\d*[a-zA-Z-][0-9a-zA-Z-]))))?(?:+([0-9a-zA-Z-]+(?:.[0-9a-zA-Z-]+)*))?: No such file or directory
/config/www/nextcloud/version.php:$OC_Version = array(20,0,1,1);
/config/www/nextcloud/version.php:$OC_VersionString = '20.0.1';
/config/www/nextcloud/version.php:$OC_Edition = '';
/config/www/nextcloud/version.php:$OC_VersionCanBeUpgradedFrom = array (
/config/www/nextcloud/version.php: 'nextcloud' =>
/config/www/nextcloud/version.php: 'owncloud' =>
/config/www/nextcloud/version.php:$vendor = 'nextcloud';
Anyone able to spot the problem?
Update 1:
For the sake of clarity, I'm trying to run this from a bash script. I just want to fetch the version number from that file, to use it in other areas of the script.
Update 2:
Responding to the comments, I tried to login to the container first, and then run the grep, and still get the same result. Then I cat that file and it shows it's contents no problem.
Many containers don't have the GNU versions of Unix tools and their various extensions. It's popular to base containers on Alpine Linux, which in turn uses a very lightweight single-binary tool called BusyBox to provide the base tools. Those tend to have the set of options required in the POSIX specs, and no more.
POSIX grep(1) in particular doesn't have an -o option. So the command you're running is
grep \
-eo \ # specify "o" as the regexp to match
"(regexps are write-only)" \ # a filename
/config/www/nextcloud/version.php # a second filename
Notice that the grep output in the interactive shell only contains lines with the letter "o", but not for example the line just containing array.
POSIX grep doesn't have an equivalent for GNU grep's -o option
Print only the matched (non-empty) parts of matching lines, with each such part on a separate output line. Output lines use the same delimiters as input....
but it's easy to do that with sed(1) instead. Ask it to match some stuff, the regexp in question, and some stuff, and replace it with the matched group.
sed -e 's/.*\(any regexp here\).*/\1/' input-file
(POSIX sed only accepts basic regular expressions, so you'll have to escape more of the parentheses.)
Well, for any potential future readers, I had no luck getting grep to do it, I'm sure it was my fault somehow and not grep's, but thanks to the help in this post I was able to use awk instead of grep, like so:
docker exec -it 1c8c05daba19 awk '/^\$OC_VersionString/ && match($0,/\047[0-9]+\.[0-9]+\.[0-9]+\047/){print substr($0,RSTART+1,RLENGTH-2)}' /config/www/nextcloud/version.php
That ended up doing exactly what I needed:
It logs into a docker container.
Scans and returns just the version number from the line I am looking for at: /config/www/nextcloud/version.php inside the container.
Exits stage left from the container with just the info I needed.
I can get right back to eating my Hot Cheetos.
when checking my $PATH on ubuntu (16.04)
I get a long list of directories, few of which even do not exist in my file
system, and some of them I just don't need:
echo $PATH
.../usr/games:/usr/local/games:/snap/bin
where they are created and how can I remove them?
I wnant to control the creation of the $PATH, rather than
correct it later by the tricks described in
https://unix.stackexchange.com/questions/108873/removing-a-directory-from-path
Some typical places where $PATH can be set when starting up a bash shell on Ubuntu include:
/etc/profile
~/.profile
~/.bashrc
where ~ represents your home directory.
Also look at any scripts called by those scripts.
There may be other things that get called when starting up a bash shell, depending on various conditions. For details, take a look at the INVOCATION section from the command:
$ man bash
See this answer from askubuntu.com to edit the path either using a text editor or the command line.
I found the answer to your question today. The path you want to edit is in /etc/environment.
I stopped a process to troubleshoot something. Now, I would like to start the process where it left off in CentOS 6.4.
This script I stopped runs a perl script in a loop to process all of the files in /dev/shm/split/. These files were split into many parts from a larger file. An example of how they are named are as follows:
file.txt.aa
file.txt.ab
file.txt.ac
...and so on.
I have identified that the script left off at file.txt.fy. So, I would like to remove all of the files in /dev/shm/split/ that are from file.txt.aa through file.txt.fy.
I tried to create a whitelist for the rm command by doing:
ls /dev/shm/split/ > whitelist
cat whitelist | egrep -v 'file.txt.[aa-fz]' | tee whitelist.tmp
This did not do what I had intended.
Please help me! Thank you!
The problem with your command is that you cannot match two characters with the square bracket pattern in bash. You should use something like that instead:
ls file.txt.[a-e]? file.txt.f[a-y]
Basically decompose your range into two ranges, the first will match .aa to .ez, and the second .fa to .fy (included).
Note that I have used the ls command here. I always find it a good idea to first echo or ls the commands/files you're going to run when the operations you do are potentially destructive. When you're sure it produces the right output, go on and use rm instead of ls.
while
grep -ir "xyz" * recursively searches through the directories and tell me that the text is present in ./x/y/z/abc.cpp
However ,
grep -ir "xyz" *.cpp offers no result.
Isn't the second command supposed to recursively grep all cpp files inside the directory ?
What am I missing here?
Grep will recurse through any directories you match with your glob pattern. (In your case, you probably do not have any directories that match the pattern "*.cpp") You could explicitly specify them: grep -ir "xyz" *.cpp */*.cpp */*/*.cpp */*/*/*.cpp, etc. You can also use the --include option (see the example below)
If you are using GNU grep, then you can use the following:
grep -ir --include "*.cpp" "xyz" .
The command above says to search recursively starting in current directory ignoring case on the pattern and to only search in files that match the glob pattern "*.cpp".
OR if you are on some other Unix platform, you can use this:
find ./ -type f -name "*.cpp" -print0 | xargs -0 grep -i "xyz"
If you are sure that none of your files have spaces in their names, you can omit the -print0 argument to find and the -0 to xargs
The command above says the following: find all files (-type f) under the current directory (./) that match the name glob/wildcard "*.cpp" (-name "*.cpp") and then print them out delimited by a null (-print0). That list of files found should be written to the stdin of the next command: xargs. xargs should read from stdin (default behavior) and split its input on nulls (-0) and then call the grep command with the specified options (grep -i "xyz") on that list of files.
If you are interested in learning more about why grep -ir "xyz" *.cpp does not work the way you think it should, you should search for "shell globbing" (here is a good first article on the subject). I'll also try to provide a quick explanation. When you type in the command grep -ir "xyz" *.cpp and hit enter, there are two programs that are involved in executing your command. The first program is your shell (and unless you've done something to customize things, you are probably usually the bash shell - if you've never heard of a shell or bash, that's where you should start looking, there are tons of good articles). Suffice it say that a shell is just a program that is designed to let you navigate the filesystem on your computer and run other programs. (In Windows, when you double click on an icon to launch a program, or open a folder to access a file, the program that you are running is explorer.exe and it is the Windows graphical shell). So, when you type the command grep -ir "xyz" *.cpp, before grep is run, the shell handles reading your command and does a few things. One of the things is does is expand glob patterns (things like *.txt or [0-9]+.pdf). Like I said, if you want to understand it, go read more about it, but the thing you should take away is that the grep command never sees the *.cpp. What happens is, the shell looks in the current directory for any files or directories with a name that match the pattern *.cpp and then replaces them on the command line BEFORE it runs the grep command. (If it doesn't find anything that matches, then it will leave the *.cpp there and grep will see it, but grep because doesn't normally do glob matching, this doesn't do anything for you).
Alternatively, when you type in grep -ir "xyz" *, what happens is that the shell replaces the * with the name of every file and directory in the current directory (because * matches anything). Let's say you had a directory that contained file1, file2, and dir1, and dir2, then the shell would perform its replacements and then execute a command that looked like this grep -ir "xyz" file1 file2 dir1 dir2, which means grep would search file1 and file2 for a line with the string xyz, and because of the -ir it also search recursively through dir1 and dir2 and search any files found for that string as well. Lastly, if you've followed everything I've said so far, then it will make sense to you that grep does have a way to use glob patterns on recursive searches, and that is to use the --include option, as in the command I described earlier: grep -ir --include "*.cpp" "xyz" ., and the reason why we put the *.cpp in quotes in that command is to prevent the shell from trying to expand the glob pattern before we run the command.
I am a newbie to shell scripting and to Linux environment as well.
In my project I am trying to search for following text from the httpd.conf file
<Directory '/somedir/someinnerdir'>
AllowOverride All
</Directory>
and then remove this text and again rewrite the same text.
The reason to do this rewriting is that the script will be run on first installation of the web app, but it may again be run some time later as other part of this shell script is performing other tasks as well. So for first time this text wont be found and will simply be written but later again when script is run this text will be found and will need to be removed and the written again.
So the part of my script with which I am trying to achieve this is something like :
grep -ve "<Directory '/somedir/someinnerdir'>\\nAllowOverride All\\n</Directory>" /etc/httpd/conf/httpd.conf > tmp_direct
echo -e "<Directory '/somedir/someinnerdir'>\\nAllowOverride All\\n</Directory>" >> tmp_direct
mv tmp_direct /etc/httpd/conf/httpd.conf
I dont have the code in front of me currently so there may be some syntactical errors above but the logic/coding is same.
Above code fragment is not able to do what I want to achieve as the grep command doesnt support multiline searching.
My OS is Fedora 8.
Can you please suggest something in this code to achieve what is needed or may be some other alternative.
Any help in this regard will be highly appreciated.
Thanks in advance.
Thanks for your replies.
Sorry for the previous bad code. Its corrected now.
Charlie and i-moan, due to workability constraints I wont be able to implement sed or perl as it will need to be added to the environment we will distribute this project in.
Steve, I want to do the check for multiple lines. I didnt put it in code blocks so it removed the directory tags. :(
So I will need to find some other way out.
Thanks again.
Best regards.
This sounds like a job for sed(1). What you want will be very close to
sed -i.bak -e '/AllowOverride All/i# ' file
to comment out the line (remember httpd.conf has comments) followed by
sed -i.bak -e 's/# AllowOverride All/AllowOverride All ' file
to pujt it back.
WARNING I haven't tried it, you want to read the man page and test it youself.
If you want to make sure you're matching an entire line, you could do:
grep -v "^AllowOverride All$"
The ^ matches the start of line and $ matches the end of line.
Does that help? I'm not exactly clear on what you're trying to do with the grep.
I'm unsure I understand the question.
Correct me if I'm wrong but your trying to add 'AllowOverride All' to the httpd.conf on the 1st running of your script. If so do you want it enabled?
Then on a 2nd pass you may want to enable / disable the command?
If I remember correctly 'AllowOverride' is only allowed in a < Directory > section So it only makes sense to add / enable in < Directory >< /Directory > definition:
If above is true you could do this in perl..
1st run: to add
perl -0777 -pi
-e 's{(.?(?!AllowOverride\s+All).?)}[\nAllowOverride
All\n$1]ixgs' httpd.conf
This will add 'AllowOverride All' to a Directory section only if it does not already contain one.
2nd run: to alter
On the 2nd run you could comment out as Charlie's suggested.. or if you like perl
perl -0777 -pi
-e's{(.?)(AllowOverride\s+All)(.?)}[$1#$2$3]ixgs' httpd.conf
and to comment in
perl -0777 -pi
-e's{(.?)(#AllowOverride\s+All)(.?)}[$1AllowOverride\s+All$3]ixgs'
httpd.conf
The regex s{}[] is quite verbose and there are better regex's to do the same thing but this is easier ( hopefully ) for a beginner to understand :).
Explanation of the perl command options
-0777 force Perl to read the whole file in one shot because 0777 is not a legal character value
-p places a loop around your script
-i lets you edit files in-place ( so your command in '-e' change the file )
-e lets you specify a single line of code on the command line
In that single line we have a regex. see perldoc perlre for info on that.
Hope that helps