Assume that there are three files in a directory of my Ubuntu-Linux. One of them is open in a music player, but two others are not open in any application and are not in use of any Process.
I want to delete those two files. In the other words, I want to detect files that are not used by any process, and then delete them.
I tried this:
rm !(lsof | grep "thePath")
but it failed. There are a problem with lsof here.
Is there any way?
Your syntax is wildly wrong. In the shell, unlike in many other programming languages, putting a command (as if it were a function call) in parentheses does not produce its result.
Instead, you want something like this:
for f in *; do
fuser -s "$f" || rm "$f"
done
I preferred fuser over lsof as it allows you to query an individual file.
Related
I have only two folders under a given directory. Is there any method to choose the second directory based on the order and not on the folder name?
Example: (I want to enter under doc2)
#ls
doc1 doc2
If you really want to use ls,
cd "$(ls -d */ | sed -n '2p')"
selects enters the second directory listed by it, independently of the number of directories provided by ls.
Parsing ls output is not a good idea generally, although it will work in most cases and will cause no harm if you are just using it in your interactive shell for fast navigation. You should not use this for serious programming.
You can use the tail command to get the last line
ls |tail -1
I am writing a bash script that looks at each file in a directory and does some sort of action to it. It's supposed to look something like this (maybe?).
for file in "$dir"* ; do
something
done
Cool, right? The problem is, this directory is being updated frequently (with new files). There is no guarantee that, at some point, I will technically be done with all the files in the dir (therefore exiting the for-loop), but not actually done feeding the directory with extra files. There is no guarantee that I will never be done feeding the directory (well... take that with a grain of salt).
I do NOT want to process the same file more than once.
I was thinking of making a while loop that runs forever and keeps updating some file-list A, while making another file-list B that keeps track of all the files I already processed, and the first file in file-list A that is not in file-list B gets processed.
Is there a better method? Does this method even work? Thanks
Edit: Mandatory "I am bash newb"
#Barmar has a good suggestion. One way to handle this is using inotify to watch for new files. After installing the inotify-tools on your system, you can use the inotifywait command to feed new-file events into a loop.
You may start with something like:
inotifywait -m -e MOVED_TO,CLOSED_WRITE myfolder |
while read dir events file, do
echo "Processing file $file"
...do something with $dir/$file...
mv $dir/$file /some/place/for/processed/files
done
This inotifywait command will generate events for (a) files that are moved into the directory and (b) files that are closed after being opened for writing. This will generally get you what you want, but there are always corner cases that depend on your particular application.
The output of inotifywait looks something like:
tmp/work/ CLOSE_WRITE,CLOSE file1
tmp/work/ MOVED_TO file2
I have some large files that I need to concatenate into one giant file to put through a software package that does not accept stdin. I would rather not duplicate the content of existing files on the hard drive if necessary, and am looking for a shortcut that basically does cat files*.txt silently when opened.
You can use process substitution to make the output of a command appear to be a file.
some_command <(cat files*.txt)
But if the application reads from standard input, you can just pipe it:
cat files*.txt | some_command
Another solution I just discovered, using named pipes...
mkfifo files.star.txt
chmod 666 files.star.txt
cat files*.txt > files.star.txt &
some_command files.star.txt
So im running a script called backup.sh. It creates a backup of a site. Now I have a file called sites.txt that has a list if sites that I need to backup. i dont want to run the script for every site that I need to backup. So what im trying to do is run is like this:
backup.sh $(cat sites.txt)
But it only backups the 1st site thats on the list then stop. any suggestions how i could keep make it go throughout the whole list?
To iterate over the lines of a file, use a while loop with the read command.
while IFS= read -r file_name; do
backup.sh "$file_name"
done < sites.txt
The proper fix is to refactor backup.sh so that it meets your expectation to accept a list of sites on its command line. If you are not allowed to change it, you can write a simple small wrapper script.
#!/bin/sh
for site in "$#"; do
backup.sh "$site"
done
Save this as maybe backup_sites, do a chmod +x, and run it with the list of sites. (I would perhaps recommend xargs -a sites.txt over $(cat sites.txt) but both should work if the contents are one token per line.)
I think this should do, provided that sites.txt has one site per line (not tested):
xargs -L 1 backup.sh < sites.txt
If you are permitted to modify backup.sh, I would enhance it so that it accepts a list of sites, not a single one. Of course, if sites.txt, is very, very large, the xargs way would still be the better one (but then without the -L switch).
I'm trying to use something along the lines of
unexpand -t 4 *.php
but am unsure how to write this command to do what I want.
Weirdly,
unexpand -t 4 file.php > file.php
gives me an empty file. (i.e. overwriting file.php with nothing)
I can specify multiple files okay, but don't know how to then overwrite each file.
I could use my IDE, but there are ~67000 instances of to be replaced over 200 files, and this will take a while.
I expect that the answers to my question(s) will be standard unix fare, but I'm still learning...
You can very seldom use output redirection to replace the input. Replacing works with commands that support it internally (since they then do the basic steps themselves). From the shell level, it's far better to work in two steps, like so:
Do the operation on foo, creating foo.tmp
Move (rename) foo.tmp to foo, overwriting the original
This will be fast. It will require a bit more disk space, but if you do both steps before continuing to the next file, you will only need as much extra space as the largest single file, this should not be a problem.
Sketch script:
for a in *.php
do
unexpand -t 4 $a >$a-notab
mv $a-notab $a
done
You could do better (error-checking, and so on), but that is the basic outline.
Here's the command I used:
for p in $(find . -iname "*.js")
do
unexpand -t 4 $(dirname $p)/"$(basename $p)" > $(dirname $p)/"$(basename $p)-tab"
mv $(dirname $p)/"$(basename $p)-tab" $(dirname $p)/"$(basename $p)"
done
This version changes all files within the directory hierarchy rooted at the current working directory.
In my case, I only wanted to make this change to .js files; you can omit the iname clause from find if you wish, or use different args to cast your net differently.
My version wraps filenames in quotes, but it doesn't use quotes around 'interesting' directory names that appear in the paths of matching files.
To get it all on one line, add a semi after lines 1, 3, & 4.
This is potentially dangerous, so make a backup or use git before running the command. If you're using git, you can verify that only whitespace was changed with git diff -w.