I am trying to iterate through files in the same directory with only one 4 in them.
Here is what I have so far. The problem with my current script is that files with any number of 4's get selected, not files with only one 4.
for i in *4*.cpp;
do
...
Sort of like [!4] but for any number of non 4 characters.
*http://www.tuxfiles.org/linuxhelp/wildcards.html
I want to iterate through file names such as me4.cpp, 4.cpp, and hi4hi.cpp
I want to ignore file names such as lala.cpp, 44.cpp, 4hi4.cpp
Thank you!
Figured it out. I tried [!4]* on a whim.
Oops turned out I didn't. That is interpreted as ([!4]) then (*)
The grep style regex you need is:
^[^4]*4[^4]*$
A bunch of not-4's after the start of the line, a 4, and another bunch of not-4's to the end of the line.
In pure shell, consider using a case statement:
for file in *4*.cpp
do
case "$file" in
(*4*4*) : Ignore;;
(*) : Process;;
esac
done
That looks for names containing 4's, and then ignores those containing 2 or more 4's.
How about using find
find ./ -regex "<regular expression>"
Assuming bash:
shopt -s extglob
for file in *([^4])4*([^4]).cpp; ...
where *([^4]) means zero or more characters that are not "4"
Related
I'm using a naming convention with number prefixes to track some files. But I am running out with 2-digit prefix. So, instead of 11.abc 12.def I want to move to 011.abc 012.def. I already have some 013.xxx 014.yyy.
Trying this in an empty directory:
touch 11.abc 12.def 013.xxx 014.yyy
ls -1 gives:
013.xxx
014.yyy
11.abc
12.def
Try #1:
This should match anything that starts with 2 digits, but not 3.
rename -n 's/^\d\d[^\d]/0$1/' *
Now I was kind of hoping that $1 would hold the match, like 11, with 0$1 giving me 011.
No such luck:
Use of uninitialized value $1 in concatenation (.) or string at (eval 2) line 1.
'11.abc' would be renamed to '0abc'
Use of uninitialized value $1 in concatenation (.) or string at (eval 2) line 1.
'12.def' would be renamed to '0def'
On the positive side, it's willing to leave 013 and 014 alone.
Try #2 rename -n 's/^\d\d[^\d]/0/' *
'11.abc' would be renamed to '0abc'
'12.def' would be renamed to '0def'
Since this is regex based, can I somehow save the match group 11 and 12?
If I can't use rename I'll probably write a quick Python script. Don't want to loop with mv on it.
And, actually, my naming covention is 2-3 digits followed by a dot, so this is a good match too.
rename -n 's/^\d\d\./<whatever needs to go here>/' *
For what it's worth, I am using the Homebrew version of rename, as I am on a mac.
try this:
rename 's/^(\d{2}\..*)/0$1/' *
rename is problematic because it's not part of POSIX (so it isn't normally available on many Unix-like systems), and there are two very different forms of it in widespread use. See Why is the rename utility on Debian/Ubuntu different than the one on other distributions, like CentOS? for more information.
This Bash code does the renaming with mv (which is part of POSIX):
#! /bin/bash -p
shopt -s nullglob # Patterns that match nothing expand to nothing.
for f in [0-9][0-9].* ; do
mv "$f" "0$f"
done
shopt -s nullglob is to prevent problems if the code is run in a directory that has no files that need to be renamed. If nullglob isn't enabled the code would try to rename a file called '[0-9][0-9].*', which would have unwanted consequences whether or not such a file existed.
I am completely new to bash script. I am trying to do something really basic before using it for my actual requirement. I have written a simple code, which should print test code as many times as the number of files in the folder.
My code:
for variable in `ls test_folder`; do
echo test code
done
"test_folder" is a folder which exist in the same directory where the bash.sh file lies.
PROBLEM: If the number of files are one then, it prints single time but if the number of files are more than 1 then, it prints a different count. For example, if there are 2 files in "test_folder" then, test code gets printed 3 times.
Just use a shell pattern (aka glob):
for variable in test_folder/*; do
# ...
done
You will have to adjust your code to compensate for the fact that variable will contain something like test_folder/foo.txt instead of just foo.txt. Luckily, that's fairly easy; one approach is to start the loop body with
variable=${variable#test_folder/}
to strip the leading directory introduced by the glob.
Never loop over the output of ls! Because of word splitting files having spaces in their names will be a problem. Sure, you could set IFS to $\n, but files in UNIX can also have newlines in their names.
Use find instead:
find test_folder -maxdepth 1 -mindepth 1 -exec echo test \;
This should work:
cd "test_folder"
for variable in *; do
#your code here
done
cd ..
variable will contain only the file names
I have a set of files I want to perform an action on in a folder that i'm hoping to write a scipt for. Each file starts with mazeFilex where x can vary from any number , is there a quick and easy way to perform an action on each file? e.g. I will be doing
cat mazeFile0.txt | ./maze_ppm 5 | convert - maze0.jpg
how can I select each file knowing the file will always start with mazeFile?
for fname in mazeFile*
do
base=${fname%.txt}
base=${base#mazeFile}
./maze_ppm 5 <"$fname" | convert - "maze${base}.jpg"
done
Notes
for fname in mazeFile*; do
This codes starts the loop. Written this way, it is safe for all filenames, whether they have spaces, tabs or whatever in their names.
base=${fname%.txt}; base=${base#mazeFile}
This removes the mazeFile prefix and .txt suffix to just leave the base name that we will use for the output file.
./maze_ppm 5 <"$fname" | convert - "maze${base}.jpg"
The output filename is constructed using base. Note also that cat was unnecessary and has been removed here.
for i in mazeFile*.txt ; do ./maze_ppm 5 <$i | convert - `basename maze${i:8} .txt`.jpg ; done
You can use a for loop to run through all the filenames.
#!/bin/bash
for fn in mazeFile*; do
echo "the next file is $fn"
# do something with file $fn
done
See answer here as well: Bash foreach loop
I see you want a backreference to the number in the mazeFile. Thus I recommend John1024's answer.
Edit: removes the unnecessary ls command, per #guido 's comment.
Its my first time to use BASH scripting and been looking to some tutorials but cant figure out some codes. I just want to list all the files in a folder, but i cant do it.
Heres my code so far.
#!/bin/bash
# My first script
echo "Printing files..."
FILES="/Bash/sample/*"
for f in $FILES
do
echo "this is $f"
done
and here is my output..
Printing files...
this is /Bash/sample/*
What is wrong with my code?
You misunderstood what bash means by the word "in". The statement for f in $FILES simply iterates over (space-delimited) words in the string $FILES, whose value is "/Bash/sample" (one word). You seemingly want the files that are "in" the named directory, a spatial metaphor that bash's syntax doesn't assume, so you would have to explicitly tell it to list the files.
for f in `ls $FILES` # illustrates the problem - but don't actually do this (see below)
...
might do it. This converts the output of the ls command into a string, "in" which there will be one word per file.
NB: this example is to help understand what "in" means but is not a good general solution. It will run into trouble as soon as one of the files has a space in its name—such files will contribute two or more words to the list, each of which taken alone may not be a valid filename. This highlights (a) that you should always take extra steps to program around the whitespace problem in bash and similar shells, and (b) that you should avoid spaces in your own file and directory names, because you'll come across plenty of otherwise useful third-party scripts and utilities that have not made the effort to comply with (a). Unfortunately, proper compliance can often lead to quite obfuscated syntax in bash.
I think problem in path "/Bash/sample/*".
U need change this location to absolute, for example:
/home/username/Bash/sample/*
Or use relative path, for example:
~/Bash/sample/*
On most systems this is fully equivalent for:
/home/username/Bash/sample/*
Where username is your current username, use whoami to see your current username.
Best place for learning Bash: http://www.tldp.org/LDP/abs/html/index.html
This should work:
echo "Printing files..."
FILES=(/Bash/sample/*) # create an array.
# Works with filenames containing spaces.
# String variable does not work for that case.
for f in "${FILES[#]}" # iterate over the array.
do
echo "this is $f"
done
& you should not parse ls output.
Take a list of your files)
If you want to take list of your files and see them:
ls ###Takes list###
ls -sh ###Takes list + File size###
...
If you want to send list of files to a file to read and check them later:
ls > FileName.Format ###Takes list and sends them to a file###
ls > FileName.Format ###Takes list with file size and sends them to a file###
I am trying to make heads or tails of a shell script. Could someone please explain this line?
$FILEDIR is a directory containing files. F is a marker in an array of files that is returned from this command:
files=$( find $FILEDIR -type f | grep -v .rpmsave\$ | grep -v .swp\$ )
The confusing line is within a for loop.
for f in $files; do
target=${f:${#FILEDIR}}
<<do some more stuff>>
done
I've never seen the colon, and the hash before in a shell script for loop. I haven't been able to find any documentation on them... could someone try and enlighten me? I'd appreciate it.
There are no arrays involved here. POSIX sh doesn't have arrays (assuming you're not using another shell based upon the tags).
The colon indicates a Bash/Ksh substring expansion. These are also not POSIX. The # prefix expands to the number of characters in the parameter. I imagine they intended to chop off the directory part and assign it to target.
To explain the rest of that: first find is run and hilariously piped into two greps which do what could have been done with find alone (except breaking on possible filenames containing newlines), and the output saved into files. This is also something that can't really be done correctly if restricted only to POSIX tools, but there are better ways.
Next, files is expanded unquoted and mutalated by the shell in more ridiculous ways for the for loop to iterate over the meaningless results. If the rest of the script is this bad, probably throw it out and start over. There's no way that will do what's expected.
The colon can be as a substring. So:
A=abcdefg
echo ${A:4}
will print the output:
efg
I'm not sure why they would use a file directory as the 2nd parameter though...
If you are having problems understanding the for loop section, try http://www.dreamsyssoft.com/unix-shell-scripting/loop-tutorial.php