All
Here i post my doubt about files with asterisk, First i create one file
touch test*
If i check ls -lrt it shows the test* file in the current.
Then i removed that file using rm *.
Then i create two files which are test1* test2* using same touch command.
If i check ls -lrt.
It displays the two files that are test1* and test2*.
Again i create test* using touch command , now i check ls -lrt.
This time it will not display the file test*.
Why the test* file is not listed ?
Thanks & regards
As * is used by your shell as universal character, when you write
touch test*
your shell will tranform it into
touch test1* test2*
If you want to create 'test*', use simple quote, which inhibit the globing function.
touch 'test*'
Normally touch command is used to create a empty file.
if file is already there it will change only the access time.
first time you are using the touch test*
that there is no test file so it will creates file names as test*
second time you are using touch test* that, time the current directory having test1* and test2* files,
so it will expand into test1* and test2* .
In that case it will change only the access time of the both file.
if you want to create one more time test* file means you can use double quotes.
Related
I want to change my PATH variable in zsh.
Problem: I don't understand where in the .zshrc file I have to make modifications.
Normally, I would look for the assignment to the PATH variable and set the values from scratch how I would like them to be (leaving all the systems binaries directories untouched).
The first lines in my .zshrc file are as follows:
# If you come from bash you might have to change your $PATH.
# export PATH=$HOME/bin:/usr/local/bin:$PATH
# Path to your oh-my-zsh installation.
export ZSH="/Users/Sam/oh-my-zsh"
export PATH=$PATH:/Applications/Postgres.app/Contents/Versions/13/bin
etc.
My actual PATH variable is:
/Library/Frameworks/Python.framework/Versions/3.9/bin:/Library/Frameworks/Python.framework/Versions/3.8/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Applications/Postgres.app/Contents/Versions/13/bin
I want to delete the directory where python3.8 is in, it's redundant.
My questions:
Do I have to change line 2 or line 7 in my .zshrc file?
Line 2 is commented out...is it executed anyway at the start of the terminal?
I have tried to comment out line 7. But the postgres directory still remained in my PATH variable which I don't understand.
The .zshrc is located in the home dir. The dot at the beginning keeps it hidden. Type ls -a from ~ directory to see it. To edit just run vim, nvim, etc as usual.
nvim ~/.zshrc
This is the command for Neovim. For your editor, sub nvim for the proper command.
Once you get in, you need only add the same export command that you would add from the command line.
export PATH=$PATH:/whatever/you/are/adding
EDIT
To remove a path variable:
First, run the command:
echo $PATH
from the command line.
Next, Copy the output to clipboard.
Finally, at the very end of the .zshrc file, add the following:
export PATH=<paste-what-you-copied-here>
Because you didn't reference $PATH after the =, this will set the path to EXACTLY what you pasted, no more, no less. Adding $PATH: as in the first example will just add whatever to the end of what is already there.
Since this gives you access to every item in the path array, deleting is just a matter of a literal highlight/select and of whatever you want deleted.
Finally, be sure that there is only one place in the file where you are editing PATH. If there are more than one, the result can be confusing to say the least.
That said, I believe the script runs top-to-bottom, so only the last mention should persist. You can take advantage of this in some situations, but for this purpose, one will suffice. XD
Be careful when you decide to fiddle with the PATH in .zshrc: Since the file is processed by every interactive subshell, the PATH would get longer and longer for each subshell, with the same directory occuring in it several times. This can become a nightmare if you later try to hunt down PATH-related errors.
Since you are using zsh, you can take advantage that the scalar variable PATH is mirrored in the array variable path, and that you can ask zsh to keep entries in arrays unique.
Hence, the first thing I would do is put a
typeset -aU path
in your .zshrc; this (due to mirroring) also keeps the entries in PATH unique. You can put this statement anywhere, but I have it for easier maintenance before my first assignment to PATH or path.
It is up to you to decide where exactly you add a new entry to PATH or path. The entries are searched in that order which is listed in the variable. You have to ask yourself two questions:
Are some directories located on a network share, where you can sometimes expect access delays (due to bad network conditions)? Those directories should better show up near the end of the path.
Do you have commands which occur in more than one directoryin your path? In this case, a path search will always find the first occurance only.
Finally, don't forget that your changes will be seen after zsh processes the file. Therefore, you could create a new subshell after having edited the file, or source .zshrc manually.
As part of our process, we get an input file in the .gz format. We need to unzip this file and add some suffix at the end of the file. The input file has timestamp so I am trying to use filter while unzipping and renaming this file.
Input file name :
Mem_Enrollment_20200515130341.dat.gz
Step 1:
Unzipping this file : (working as expected)
gzip -d Mem_Enrollment_*.dat.gz
output :
Mem_Enrollment_20200515130341.dat
Step 2: Renaming this file : (issues while renaming)
Again, I am going with the pattern but I know this won't work in this case. So, what should I do rename this file?
mv Mem_Enrollment_*.dat Mem_Enrollment_*.dat_D11
output :
Mem_Enrollment_*.dat_D11
expected output :
Mem_Enrollment_20200515130341.dat_D11
try
for fn in Mem_Enrollment_*.dat
do
mv ${fn} ${fn}_D11;
done
With just datastage you could loop over ls output from an execute command stage via "ls Mem_Enrollment_*.dat.gz" and then use an #FM as a delimiter when looping the output list. You could then breakout the gzip and rename into two separate commands, which helps with readability in your job.
Only caveat here is that the Start Loop stage doesn't accept the #FM in the delimiter due to some internal funkyness inside Datastage. So you need to set a user variable equal to it and pass that to the mark.
Here is what my directory looks like:
Test ----
|
|----One
|
|----Two
I am attempting to list the contents of Two while still being in One and I am not able to do so.
I have tried this command (as seen in a other post) : "ls Test/" and it says No such file or directory. I have also tried ls Test/Two/ and it still does not work.
If you are in One and you want to list the contents of Two, you should go up to the parent directory using ..:
ls ../Two
../ will place you in the Test directory, from there, you can go to Two with no problem. If you have more depth levels, just add more ../ to go up one directory each time, but mind which is your current directory when running the command.
what does this command provide you in terminal.
ls -al Test //a flag is used for hidden file
Using Make is there a nice way to depend on a directories contents.
Essentially I have some generated code which the application code depends on. The generated code only needs to change if the contents of a directory changes, not necessarily if the files within change their content. So if a file is removed or added or renamed I need the rule to run.
My first thought is generate a text file listing of the directory and diff that with the last listing. A change means rerun the build. I think I will have to pass off the generate and diff part to a bash script.
I am hoping somehow in their infinite intelligence might have an easier solution.
Kudos to gjulianm who got me on the right track. His solution works perfect for a single directory.
To get it working recursively I did the following.
ASSET_DIRS = $(shell find ../../assets/ -type d)
ASSET_FILES = $(shell find ../../assets/ -type f -name '*')
codegen: ../../assets/ $(ASSET_DIRS) $(ASSET_FILES)
generate-my-code
It appears now any changes to the directory or files (add, delete, rename, modify) will cause this rule to run. There is likely some issue with file names here (spaces might cause issues).
Let's say your directory is called dir, then this makefile will do what you want:
FILES = $(wildcard dir/*)
codegen: dir # Add $(FILES) here if you want the rule to run on file changes too.
generate-my-code
As the comment says, you can also add the FILES variable if you want the code to depend on file contents too.
A disadvantage of having the rule depend on a directory is that any change to that directory will cause the rule to be out-of-date — including creating generated files in that directory. So unless you segregate source and target files into different directories, the rule will trigger on every make.
Here is an alternative approach that allows you to specify a subset of files for which additions, deletions, and changes are relevant. Suppose for example that only *.foo files are relevant.
# replace indentation with tabs if copy-pasting
.PHONY: codegen
codegen:
find . -name '*.foo' |sort >.filelist.new
diff .filelist.current .filelist.new || cp -f .filelist.new .filelist.current
rm -f .filelist.new
$(MAKE) generate
generate: .filelist.current $(shell cat .filelist.current)
generate-my-code
.PHONY: clean
clean:
rm -f .filelist.*
The second line in the codegen rule ensures that .filelist.current is only modified when the list of relevant files changes, avoiding false-positive triggering of the generate rule.
I have a list of files with their full path in a single text file. I would like to open them all at once in Windows. The file extension will tell Windows what programme to use. Can I do this straight from the command line or would I need to make a batch file? Tips on how to write the batch file appreciated.
My text file looks like the following:
J:/630/630A/SZ299_2013-04-19_19_36_52_M01240.WAV
J:/630/630A/SZ299_2013-04-19_20_15_39_M02312.WAV
J:/630/630A/SZ299_2013-04-19_21_48_07_M04876.WAV
etc
The .WAV extension is associated with Adobe Audition, which is a sound editing programme. When each path is hyperlinked in an Excel column, they can be opened with one click. Clicking on the first link will open both Audition and the hyperlinked file in it. Clicking another hyperlink will open the next file in the same instance of the programme. But this is too slow for hundreds of paths. If I open many files straight from R, e.g.
shell("J:/630/630A/SZ299_2013-04-19_19_36_52_M01240.WAV", intern=TRUE)
shell("J:/630/630A/SZ299_2013-04-19_20_15_39_M02312.WAV", intern=TRUE)
etc
each file will be opened in a new instance of the programme, which is nasty. So batch seems preferable.
for /f "delims=" %%a in (yourtextflename) do "%%a"
should do this as a batch line.
You could run this directly from the prompt if you like, but you'd need to replace each %% with % to do so.
It's a lot easier to put the code into a batch:
#echo off
setlocal
for /f "delims=" %%a in (%1) do "%%a"
then you'd just need to enter
thisbatchfilename yourtextfilename
and yourtextfilename will be substituted for %1. MUSCH easier to type - and that's what batch is all about - repetitive tasks.
Following on from this post, which uses the identify function in R to create a subset selection of rows (from a larger dataset called "testfile") by clicking on coordinates in a scatterplot. One of the columns contains the list of Windows paths to original acoustic datafiles. The last line below will open all files in the listed paths in only one instance of the programme linked to the Windows file extension.
selected_rows = with(testfile, identify(xvalue, yvalue))
SEL <-testfile[selected_rows,]
for (f in 1:nrow(SEL)){system2("open",toString(SEL[f,]$path))}