How to rename the files to extracted 7 last letters from original name

hirom · 06-05-2022, 10:08 AM

Hello, experts,
I need to rename a lot of files to extracted 7 last letters from original name;
ex. from "zyxhheddbaaa00106.jpg" to "106.jpg"
As the original filename text length varies, it seems that I need to use both "rev" and "cut" command.

To begin with "rev" command, I thought the command below work,

Code:

for f in `find . -name *.*`; do g="$(rev $(basename $f))" | mv $f "$(dirname $f)/$(basename $g)" ; done

However, I got the error message below.

basename: missing operand
Try 'basename --help' for more information.
rev: cannot open zzzhheddbaaa0381.jpg: No such file or directory
mv: './066/zzzhheddbaaa0381.jpg' and './066/zzzhheddbaaa0381.jpg' are the same file

My questions are:

Regarding "basename": I don't understand this error as in the next line it seems that the file name is read correctly.
Regarding "rev": How to reverse the text itself rather than reading a file?

I appreciate your advice, thank you in advance.

wpeckham · 06-05-2022, 10:19 AM

First, you are asking two questions: one about extracting the last seven characters from a string and another about renaming files. These can easily be combined into one process, but ARE different questions.

Second, are you doing this in BASH? This may be important in that if a shell with string handling and substring features is involved then no external utilities should be required for extracting the last seven characters form a string.

On the renaming a file, I would add some handling in the case that two file names might happen to have the same last seven characters, even if all others differ.

Finally a question of my own, before we discuss code: is this homework? If it is, what have you done to address it so far? Can we see your work?

teckk · 06-05-2022, 10:37 AM

Example:

Code:

a=(
zyxhheddbaaa00106.jpg
hheddbaaa00106.jpg
eddbaaa00106.jpg
dbaaa00106.jpg
baaa00106.jpg
aaa00106.jpg
a00106.jpg
0106.jpg
)

for i in "${a[@]}"; do
    echo ""$i" ----> "${i[@]: -7}""
done

Turbocapitalist · 06-05-2022, 10:51 AM

If you use rename then you can use full perl regular expressions to manipulate the name.

teckk · 06-05-2022, 10:59 AM

Quote:

for f in `find . -name *.*`

For f in current dir find everything.

Code:

for f in *; do
    echo "mv "$f" --> "${f[@]: -7}""
    sleep 1
done

boughtonp · 06-05-2022, 11:51 AM

Quote:

Originally Posted by hirom

I need to rename a lot of files to extracted 7 last letters from original name;
ex. from "zyxhheddbaaa00106.jpg" to "106.jpg"

WHY?

How certain are you that it's always seven characters and the result is always unique and correct?

Have you confirmed that you'll never have "whatever01106.jpg" or "whatever00106.jpeg"?

Are you aware what might happen if such a script is run on a server and is inadvertently used against a file named ".htaccess" ?

teckk · 06-05-2022, 01:56 PM

Quote:

Are you aware what might happen if such a script is run on a server and is inadvertently used against a file named ".htaccess" ?

That's a good thought.

Let me see.

This doesn't get hidden files

Code:

for i in *; do
    if [[ "$i" =~ ^\. ]]; then
        echo "Hidden file --> "$i""
    else 
        echo "Not hidden --> "$i""
    fi
done

This does

Code:

for i in .*; do
    if [[ "$i" =~ ^\. ]]; then
        echo "Hidden file --> "$i""
    else 
        echo "Not hidden --> "$i""
    fi
done

These will get everything

Code:

shopt -s dotglob
for i in *; do
    if [[ "$i" =~ ^\. ]]; then
        echo "Hidden file --> "$i""
    else 
        echo "Not hidden --> "$i""
    fi
done

for i in .[!.]* *; do
    if [[ "$i" =~ ^\. ]]; then
        echo "Hidden file --> "$i""
    else 
        echo "Not hidden --> "$i""
    fi
done

hirom · 06-07-2022, 11:55 AM

Thank you all for your comments and thoughtful discussions.
I have only limited access time to the Linux machine, so I will try the commands tomorrow.
The data is jpg files of a continuous subjective experiment stored in different folders /"experiment_No"/"Subject's_name_etc"-"3_digits_number".jpg .
There are images with same 3 digits number in different folders, but thankfully, they are not in the same folder.
The reason why I need to delete the letters is to delete the subjects' name to make it anonymous before passing the data to an external collaborator.
However, I learned from you that it is important to make commands as safe as possible.