I have a list of files in a folder that need to be fed piped through to more commands, if I know the position of the files when using ls -v file_*.nc is it possible to remove/ignore files based on their position? So if ls -v file_*.nc returns 300 files, and I want files 8,73, and 151 removed from the pipe I could do something like ls -v file_*.nc | {remove 8,73,151} | do other stuff.
I don't want to delete/move the files, I just don't want them piped through to the next command.
If you wanted to filter out from the input as you said : is it possible to remove/ignore files
you can use grep -v <PATTERN> which -v is an exclusive match option.
input files
ls -v1 txt*
txt
txt-1
txt-2
txt-3
txt-4
txt-5
txt-6
txt-7
txt-8
txt-9
txt-10
then ignore any file which contains either 7, 8, 9
ls -v txt* | grep -v '[789]'
txt
txt-1
txt-2
txt-3
txt-4
txt-5
txt-6
txt-10
removed/ignored
txt-7
txt-8
txt-9
I need to get all files using shell script with some name X less files with name Y.
I'm trying to using grep -l -v to do it but i don`t really know how to use it.
Considering that you want to get files from a dir:
Try this:
ls | grep "X" | grep -v "Y"
I created 3 files in a directory with the following names:
11 13 9
Problem, as I created file 9 after 13 it is placed after file 13 when I do the ls command.
Do you have any idea to make the ls command sort the files in the numerical order, like this:
9 11 13
Look at the man page for ls.
From there-
-v natural sort of (version) numbers within text.
You'll find that the command ls -v does what you want.
If you want the file names on different lines then you can do ls -1v.
List with lines without columns:
ls -x
Using tr to avoid multiple lines output:
ls | tr "\n" " "
And to ensure to accurately force ascending order:
ls -v | tr "\n" " "
Some useful and essential information from linux.org about ls.
Unfortunately, ls -v on macOS and FreeBSD does not perform a natural sort on the list of files. FreeBSD ls does not support this flag at all. On macOS it can be used to
force unedited printing of non-graphic characters; this is the default when output is not to a terminal.
If you badly need the GNU extension of -v to the ls utility, you can install the GNU ls and then use alias ls=gls to use the GNU ls instead of the default ls. GNU ls usually comes with the coreutils package, so, e.g.,
On macOS: brew install coreutils
On FreeBSD: pkg install coreutils
I need to write a shell script that does the following:
In a given folder with files that fit the pattern: update-8.1.0-v46.sql I need to find the maximum version
I need to write the maximum version I've found into a configuration file
For 1, I've found the following answer: Shell script: find maximum value in a sequence of integers without sorting
The only problem I have is that I can't get down to a list of only the versions,
I tried:
ls | grep -o "update-8.1.0-v\(\d*\).sql"
but I get the entire file name in return and not just the matching part
Any ideas?
Maybe move everything to awk?
I ended up using:
SCHEMA=`ls database/targets/oracle/ | grep -o "update-$VERSION-v.*.sql" | sed "s/update-$VERSION-v\([0-9]*\).sql/\1/p" | awk '$0>x{x=$0};END{print x}'`
based on dreamer's answer
you can use sed for this:
echo "update-8.1.0-v46.sql" | sed 's/update-8.1.0-v\([0-9]*\).sql/\1/p'
The output in this case will be 46
grep isn't really the best tool for extracting captured matches, but you can use look-behind assertions if you switch it to use perl-like regular expressions. Anything in the assertion will not be printed when using the -o flag.
ls | grep -Po "(?<=update-8.1.0-v)\d+"
46
Let's say that during your workday you repeatedly encounter the following form of columnized output from some command in bash (in my case from executing svn st in my Rails working directory):
? changes.patch
M app/models/superman.rb
A app/models/superwoman.rb
in order to work with the output of your command - in this case the filenames - some sort of parsing is required so that the second column can be used as input for the next command.
What I've been doing is to use awk to get at the second column, e.g. when I want to remove all files (not that that's a typical usecase :), I would do:
svn st | awk '{print $2}' | xargs rm
Since I type this a lot, a natural question is: is there a shorter (thus cooler) way of accomplishing this in bash?
NOTE:
What I am asking is essentially a shell command question even though my concrete example is on my svn workflow. If you feel that workflow is silly and suggest an alternative approach, I probably won't vote you down, but others might, since the question here is really how to get the n-th column command output in bash, in the shortest manner possible. Thanks :)
You can use cut to access the second field:
cut -f2
Edit:
Sorry, didn't realise that SVN doesn't use tabs in its output, so that's a bit useless. You can tailor cut to the output but it's a bit fragile - something like cut -c 10- would work, but the exact value will depend on your setup.
Another option is something like: sed 's/.\s\+//'
To accomplish the same thing as:
svn st | awk '{print $2}' | xargs rm
using only bash you can use:
svn st | while read a b; do rm "$b"; done
Granted, it's not shorter, but it's a bit more efficient and it handles whitespace in your filenames correctly.
I found myself in the same situation and ended up adding these aliases to my .profile file:
alias c1="awk '{print \$1}'"
alias c2="awk '{print \$2}'"
alias c3="awk '{print \$3}'"
alias c4="awk '{print \$4}'"
alias c5="awk '{print \$5}'"
alias c6="awk '{print \$6}'"
alias c7="awk '{print \$7}'"
alias c8="awk '{print \$8}'"
alias c9="awk '{print \$9}'"
Which allows me to write things like this:
svn st | c2 | xargs rm
Try the zsh. It supports suffix alias, so you can define X in your .zshrc to be
alias -g X="| cut -d' ' -f2"
then you can do:
cat file X
You can take it one step further and define it for the nth column:
alias -g X2="| cut -d' ' -f2"
alias -g X1="| cut -d' ' -f1"
alias -g X3="| cut -d' ' -f3"
which will output the nth column of file "file". You can do this for grep output or less output, too. This is very handy and a killer feature of the zsh.
You can go one step further and define D to be:
alias -g D="|xargs rm"
Now you can type:
cat file X1 D
to delete all files mentioned in the first column of file "file".
If you know the bash, the zsh is not much of a change except for some new features.
HTH Chris
Because you seem to be unfamiliar with scripts, here is an example.
#!/bin/sh
# usage: svn st | x 2 | xargs rm
col=$1
shift
awk -v col="$col" '{print $col}' "${#--}"
If you save this in ~/bin/x and make sure ~/bin is in your PATH (now that is something you can and should put in your .bashrc) you have the shortest possible command for generally extracting column n; x n.
The script should do proper error checking and bail if invoked with a non-numeric argument or the incorrect number of arguments, etc; but expanding on this bare-bones essential version will be in unit 102.
Maybe you will want to extend the script to allow a different column delimiter. Awk by default parses input into fields on whitespace; to use a different delimiter, use -F ':' where : is the new delimiter. Implementing this as an option to the script makes it slightly longer, so I'm leaving that as an exercise for the reader.
Usage
Given a file file:
1 2 3
4 5 6
You can either pass it via stdin (using a useless cat merely as a placeholder for something more useful);
$ cat file | sh script.sh 2
2
5
Or provide it as an argument to the script:
$ sh script.sh 2 file
2
5
Here, sh script.sh is assuming that the script is saved as script.sh in the current directory; if you save it with a more useful name somewhere in your PATH and mark it executable, as in the instructions above, obviously use the useful name instead (and no sh).
It looks like you already have a solution. To make things easier, why not just put your command in a bash script (with a short name) and just run that instead of typing out that 'long' command every time?
If you are ok with manually selecting the column, you could be very fast using pick:
svn st | pick | xargs rm
Just go to any cell of the 2nd column, press c and then hit enter
Note, that file path does not have to be in second column of svn st output. For example if you modify file, and modify it's property, it will be 3rd column.
See possible output examples in:
svn help st
Example output:
M wc/bar.c
A + wc/qax.c
I suggest to cut first 8 characters by:
svn st | cut -c8- | while read FILE; do echo whatever with "$FILE"; done
If you want to be 100% sure, and deal with fancy filenames with white space at the end for example, you need to parse xml output:
svn st --xml | grep -o 'path=".*"' | sed 's/^path="//; s/"$//'
Of course you may want to use some real XML parser instead of grep/sed.