I am a newbie to Linux and am trying to extract portion of a filename from the absolute path in a bash script. For example, if the path is /opt/data/filename-attribute.dat, I am able to get the path of the directory and the file as follows:
sourcedir=`dirname $path`
name=`basename $path`
I would like to extract attribute from the file and was wondering if there was a quick way in shell script to perform this. I can get filename-attribute by
f=${name%%[.]*}
and would like to extract just the attribute.
The easiest way is just to do it in two steps:
f="${name%.*}" # strip everything from the last dot onward
f="${f##*-}" # strip everything up through the last hyphen
If I understand you right
a="${f#*-}"
Related
Ok so I kinda dropped the ball. I was trying to understand how things work. I had a few html files on my computer that I was trying to rename as txt files. This was strictly a learning exercise. Following the instructions I found here using this code:
for file in *.html
do
mv "$file" "${file%.html}.txt"
done
produced this error:
mv: rename *.html to *.txt: No such file or directory
Long story short I ended up going rogue and renaming the html files, as well as a lot of other non html files as txt files. So now I have files labeled like
my_movie.mp4.txt
my_song.mp3.txt
my_file.txt.txt
This may be a really dumb question but.. Is there a way to check if a file has two extensions and if yes remove the last one? Or any other way to undo this mess?
EDIT
Doing this find . -name "*.*.txt" -exec echo {} \; | cat -b seems to tell me what was changed and where it is located. The cat -b part is not necessary but I like it. This still doesn't fix what I broke though.
I'm not sure if terminal can check for extensions "twice", but you can check for . in every name an if there's more than one occurence of ., then your file has more extensions. Then you can cut the extension off with finding first occurence of . in a string when going backwards... or last one if checking characters in string in a normal way.
I have a faster option for you if you can use python. You can strip the extension with:
for file in list_of_files:
os.rename(file,os.path.splitext(file)[0])
which can give you from your file.txt.txt your file.txt
Example:
You wrote that your command tells you what has changed, so just take those changed files and dump them into a file(path to file per line). Then you can easily run this:
with open('<path to list>') as f:
list_of_files = f.readlines()
for file in list_of_files:
os.rename(file.strip('\n'), os.path.splitext(file.strip('\n'))[0])
If not, then you'd need to get the list from python:
import os
results = []
for root, folder, filenames in os.walk(<your path to folder>):
for filename in filenames:
if filename.endswith('.txt.txt'):
results.append(os.path.join(root, filename))
With this you got a list of files ending with .txt.txt like this <your folder>\\<path_to_file>.
Get a path to your directory used in os.walk() without folder's name(it's already in list) so it'll be like this:
e.g. os.walk('/home/me/directory') -> path='/home/me/' and res is item already in a list, which looks like directory/...
for res in results:
path = '' # set the path here
file = os.path.join(path,r)
os.rename(file, os.path.splitext(file)[0])
Depending on what files you want to find change .txt.txt in if filename.endswith('...') to whatever you like and os.rename() will take file's name without extension which in your case means it strips the additional extension you don't want to have.
I am trying to create a zsh script to test my project. The teacher supplied us with some input files and expected output files. I need to diff the output files from myExecutable with the expected output files.
Question: Does $iF contain a string in the following code or some kind of bash reference to the file?
#!/bin/bash
inputFiles=~/project/tests/input/*
outputFiles=~/project/tests/output
for iF in $inputFiles
do
./myExecutable $iF > $outputFiles/$iF.out
done
Note:
Any tips in fulfilling my objectives would be nice. I am new to shell scripting and I am using the following websites to quickly write the script (since I have to focus on the project development and not wasting time on extra stuff):
Grammar for bash language
Begginer guide for bash
As your code is, $iF contains full path of file as a string.
N.B: Don't use for iF in $inputFiles
use for iF in ~/project/tests/input/* instead. Otherwise your code will fail if path contains spaces or newlines.
If you need to diff the files you can do another for loop on your output files. Grab just the file name with the basename command and then put that all together in a diff and output to a ".diff" file using the ">" operator to redirect standard out.
Then diff each one with the expected file, something like:
expectedOutput=~/<some path here>
diffFiles=~/<some path>
for oF in ~/project/tests/output/* ; do
file=`basename ${oF}`
diff $oF "${expectedOutput}/${file}" > "${diffFiles}/${file}.diff"
done
I am writing a bash script that will output a .tgz file to a specific directory, /tmp/ by default
I would like to provide an option to override this directory and I have chosen to do so using arguments provided at the command line
while getopts d: option
do
case "${option}" in
d) dir=${OPTARG};;
esac
done
As written, this works but I've run into a snag depending on user input
The name of my .tgz file is also a variable and my code that brings this all together is
output="$dir""$name"
The problem that I run into is if the user runs
./script -d /home/user
My resulting path and filename end up as
/home/userfilename.tgz
I need to either enforce a requirement for a trailing / or insert one if the user did not.
While it works, if I change my output variable to
output="$dir"/"$name"
If the user does provide a trailing / I end up with something like this and I am trying to keep my output aesthetic.
/home/user//filename.tgz
Any input would be greatly appreciated.
Add the line
output="${output//\/\///}"
after joining dir and name.
It looks complicated, but what it does is it replaces two slashes with one.
You may find more info in here.
I'm using ImageMagick to do some image processing from the commandline, and would like to operate on a list of files as specified in foo.txt. From the instructions here: http://www.imagemagick.org/script/command-line-processing.php I see that I can use Filename References from a file prefixed with #. When I run something like:
montage #foo.txt output.jpg
everything works as expected, as long as foo.txt is in the current directory. However, when I try to access bar.txt in a different directory by running:
montage /some_directory/#bar.txt
output2.jpg
I get:
montage: unable to open image
/some_directory/#bar.txt: No such file
or directory # blob.c/OpenBlob/2480.
I believe the issue is my syntax, but I'm not sure what to change it to. Any help would be appreciated.
Quite an old entry but it seems relatively obvious that you need to put the # before the full path:
montage #/some_directory/bar.txt output2.jpg
As of ImageMagick 6.5.4-7 2014-02-10, paths are not supported with # syntax. The # file must be in the current directory and identified by name only.
I haven't tried directing IM to pull the list of files from a file, but I do specify multiple files on the command line like this:
gm -sOutputFile=dest.ext -f file1.ppm file2.ppm file3.ppm
Can you pull the contents of that file into a variable, and then let the shell expand that variable?
I'm trying to use the rename command in a Terminal in Ubuntu to append a string to the beginning of some avi file names as follows.
rename -n 's/(\w)\.avi$/String_to_add__$1\.avi/' *.avi
So I expect the following:
String_to_add_MyMovie.avi
Problem is that when I run the command it appends the string to the end of the file name, so I end up with the following:
MyMovie_String_to_add_.avi
I'm not sure if I have the perlexpr syntax wrong or something else. Any insight is appreciated.
UPDATE:
Thanks for the suggestions, I tried the suggestions from alno and plundra and made the following modification:
rename -n 's/(\w+)\.avi$/String_to_add__$1\.avi/' *.avi
But now the file gets the string inserted in the middle of the name as follows:
My_String_to_add_Movie
My apologies though, I neglected to mention that the titles are preceded by 3 numeric values, so the file name nomenclature is {3 numbers}-My_Movie.avi so for example 001-My_Movie.avi. But I didn't think this would make a difference since I'm assuming \w+ matches alphanumeric characters, might the '-' be the issue?
Haven't tried Christian's approach yet, I want to be able to use the rename command, or at least understand why it's not working before I try a different approach.
I don't think rename -n is standard. You could do this:
for i in *.avi; do mv $i String_to_add_$i; done
You're only matching a single character with \w, you want \w+, so the complete line would be:
rename -n 's/(\w+)\.avi$/String_to_add__$1\.avi/' *.avi
Correct version:
rename -n 's/(\w+)\.avi$/String_to_add__$1\.avi/' *.avi
You simply forgot + after \w, so it tried to match only one character.