Bash Variables containing filepaths - linux

I'm writing a script that needs to find a file in a directory based on the user input. That file contains a filepath, and I need to use that filepath as a variable so I can use it later in a mv command. So far :-
read x
path = `cat ~/filepaths/$x`
Later it needs to move a file from trash using the filepath read from this file
mv ~/trash/$x $path
Currently, it doesn't appear to work, and hangs when it runs. Is there something stupid I've missed here?
EDIT: Solved, was a stupid syntax mistake. Thanks for your help!

Remove the spaces around the assignment:
path=`cat ~/filepaths/$x`
or:
path=$(< ~/filepaths/$x)

Related

Add extra file extension to all filenames in a directory via Linux command line

I want to add the ".sbd" after all files ending on ".utf8" in a directory
I do not want to replace the extensions, but really want to add them so the filenames will look like "filename.utf8.sbd"
I think I should adapt the following code, but don't manage to find out exactly how
for f in *.utf8 ; do mv "$f" "$f.sbd" ; done
Can anyone help me? I am very new to the command line
Thanks a bunch!
Your code should work if no file has spaces (or other "special" character) in the name and if the directory is not pathologically big.
In those cases, you can use something like this:
ls|grep '*.utf8$'|while read i; do mv "$i" "$i.sbd"; done

Is there a way to undo a batch-rename of file extensions?

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.

unix - get substring of a file name

If I have a folder called myfiles/ which has a bunch of python files in it, in a shell script like the following:
for k in myfiles/*.py
do
// code here?
done
How do I print for each k a string that's just --name-of-file--.py ?
If I do
echo $k
as is, it prints myfiles/--name-of-file--.py
I'm very new to shell scripting, but it seems like the cut function attempts to cut the contents of the file and not just the file name (and I don't really know how to use cut).
To be clear, I'd like to know how to get rid of the folder name when printing.
basename "$k"
Or if you want to avoid spawning so many processes, this is more efficient:
echo ${k##*/}

What does this bash script command mean (sed - e)?

I'm totally new to bash scripting but i want to solve this problem..
the command is:
objfil=`echo ${srcfil} | sed -e "s,c$,o,"`
the idea about the bash script program is to check for the source files, and check if there is an adjacent object file in the OBJ directory, if so, the rest of the program runs smoothly, if not, the iteration terminates and skips the current source file, and moves on to the next one.. it works with .c files but not on the headers, since the object filenames depend on .c files.. i want to write this command so it checks the object files not just the .c but the .h files too.. but without skipping them. i know i have to do something else too, but i need to understand what this line of command does exactly to move on. Thanks. (Sorry for my english)
UPDATE:
if test -r ${curOBJdir}/${objfil}
then
cp -v ${srcfil} ./SAVEDSRC/${srcfil}
fdone="NO"
linenums=ALL
else
fdone="YES"
err="${curOBJdir}/${objfil} is missing - ${srcfil} skipped)"
echo ${err}
echo ${err} >>${log}
fi
while test ${fdone} == "NO"
do
#rest of code ...
here is the rest of the program.. i tried to comment out the "test" part to ignore the comparison just because i only want my script to work on .h files, but without checking the e.g abc.h files has an abc.o file.. (the object file generation is needed because the end of the script there's a comparison between the hexdump of the original and modified object files). The whole script is for changing the basic types with typedefs like int to sint32_t for example.
This concrete command will substitute all c's right before line-end to o:
srcfill=abcd.c
objfil=`echo ${srcfil} | sed -e "s,c$,o,"`
echo $objfil
Output:
abcd.o
P.S. It uses a different match/replace separator: default is / but it uses ,.

All files in one dir, linux

Today I tried a script in linux to get all files in one dir. It was pretty straightforward, but I found something interesting.
#!/bin/bash
InputDir=/home/XXX/
for file in $InputDir'*'
do
echo $file
done
The output is:
/home/XXX/fileA /home/XXX/fileB
But when I just input the dir directly, like:
#!/bin/bash
InputDir=/home/XXX/
for file in /home/XXX/*
do
echo $file
done
The output is:
/home/XXX/fileA
/home/XXX/fileB
It seems, in the first script, there was only one loop and all the file names were stored in the variable $file in the FIRST loop, separated by space. But in the second script, one file name was stored in $file just in one loop, and there were more than one loop. What is exactly the difference between these two scripts?
Thanks very much, maybe my question is a little bit naive..
The behavior is correct and "as expected".
for file in $InputDir'*' means assign "/home/XXX/*" to $file (note the quotes). Since you quoted the asterisk, it will not be executed at this time. When the shell sees echo $file, it first expands the variables and then it does glob expansion. So after the first step, it sees
echo /home/XXX/*
and after glob expansion, it sees:
echo /home/XXX/fileA /home/XXX/fileB
Only now, it will execute the command.
In the second case, the pattern /home/XXX/* is expanded before the for is executed and thus, each file in the directory is assigned to file and then the body of the loop is executed.
This will work:
for file in "$InputDir"*
but it's brittle; it will fail, for example, when you forget to add a / to the end of the variable $InputDir.
for file in "$InputDir"/*
is a little bit better (Unix will ignore double slashes in a path) but it can cause trouble when $InputDir is not set or empty: You'll suddenly list files in the / (root) folder. This can happen, for example, because of a typo:
inputDir=...
for file in "$InputDir"/*
Case matters on Unix :-)
To help you understand code like this, use set -x ("enable tracing") in a line before the code you want to debug.
The difference is the quoting of '*'. In the first case the loop only executes once, with $file equal to /home/XXX/* which then expands to all the files in the directory when passed to echo. In the second case it executes once per file, with $file equal to each file name in turn.
Bottom line - change:
for file in $InputDir'*'
to:
for file in $InputDir*
or, better, and to make it more readable - change:
InputDir=/home/XXX/
for file in $InputDir'*'
to:
InputDir=/home/XXX
for file in $InputDir/*

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