How to rename files using certain string inside each file? - regex

Question

I have a list of html files that contain a certain tag in each file as below:
<div id="myID" style="display:none">1_34876</div>
I would like to search for that tag in each file and rename each file according to the number within that tag, i.e rename the file containing the tag above to 1_34876.html
and so forth..
Is there a regex or bash command using grep or awk that can accomplish this?
So far I was able to grep each file using the following command but stuck on how to rename the files:
grep '<div id="myID" style="display:none">.*</div>' ./*.html
An additional bonus would be if the command doesn't overwrite duplicate files, e.g. if another file contains the 1_34876 tag above then the second file would be renamed as 1_34876 v2.html or something similar.
Kindly advice if this can be achieved in a way that doesn't require programming.
Many thanks indeed.
Ali

Answer 1

You can use the following script to achieve your goal. Note, for the script to work on macOS, you either have to install GNU grep via Homebrew, or substitute the grep call with ggrep.
The script will search the current directory and all its subdirectories for *.html files.
It will substitute only the names of the files that contain the specific tag.
For multiple files that containt the same tag, each subsicuent file apart from the first will have an identifier appended to its name. E.g., 1_234.html, 1_234_1.html, 1_234_2.html
For files that contain multiple tags, the first tag encountered will be used.
#!/bin/bash
rename_file ()
{
# Check that file name received is an existing regular file
file_name="$(realpath "${1}")"
if [ ! -f "${file_name}" ]; then
echo "No argument or non existing file or non regular file provided"
exit 1
fi
# Get the tag number. If the number does not exist, the variable tag will be
# empty. The first tag on a file will be used if there are multiple tags
# within a file.
tag="$(grep -oP -m 1 '(?<=<div id="myID" style="display:none">).*?(?=</div>)' \
-- "${file_name}")"
# Rename the file only if it contained a tag
if [ -n "${tag}" ]; then
file_path="$(dirname "${file_name}")"
# Change directory to the file's location silently
pushd "${file_path}" > /dev/null || return
# Check for multiple occurences of files with the same tag
if [ -e "${tag}.html" ]; then
counter="$(find ./ -maxdepth 1 -type f -name "${tag}.html" -o -name "${tag}_*.html" | wc -l)"
tag="${tag}_${counter}"
fi
# Rename the file
mv "${file_name}" "${tag}.html"
# Return to previous directory silently
popd > /dev/null || return
fi
}
# Necessary in order to call rename_file from find command within main
export -f rename_file
# The entry point function of the script. This function searches for all the
# html files in the directory that the script is run, and all subdirectories.
# The function calls rename_files upon each of the found files.
main ()
{
find ./ -type f -name "*.html" -exec bash -c 'rename_file "${1}"' _ {} \;
}
main

Answer 2

As we do not know exact content of the files and folders we need to take care about
Check that tag is unique
File with such name does not exists
Do not rename already renamed files
Steps:
Search for files with specidied tags grep -o '<div id="myID" style="display:none">.*</div>' /*.html
it will provide us output in format file_path:tag
Extract file_path using regexp [^:]+ (not : one or more symbols )
with -o (exact match) and get first occurence using head -1
Get new file name from tag using regexp ">.<" and then remowing "<>" using sed
we can use here one regexp to skip <> but it will be more complex and not so readable grep -oP ">\K.(?=<)"
Rename files , log Errors and script actions, return non zero exit code in case of issues
Unless it is really required better to use functions with local variables declaration (decalre using function fn_rename_html_files {} instead of fn_rename_html_files() {} as if we have complex logic with nesting functions you may change other functions variables and debugging will be not so easy)
function fn_rename_html_files {
typeset l_files_path="${1-.}"
typeset l_html_ext=".html"
typeset l_proc_exit_code=0
typeset l_proc_name="${FUNCNAME[0]}"
typeset l_files_to_search="${l_files_path}/*${l_html_ext}"
typeset l_tag_reg_exp='<div id="myID" style="display:none" *>.*</div>'
typeset l_matched_files=$(grep -o "$l_tag_reg_exp" $l_files_to_search | sort -u)
typeset l_prev_file_path=""
# loop through matching files
while IFS= read -r l_file_path_with_match_tag
do
l_current_file_path=$(echo "$l_file_path_with_match_tag" | egrep -o "([^:])+" | head -1 )
l_current_file_name=$(basename "$l_current_file_path")
#echo "l_current_file_path $l_current_file_path "
#echo "l_current_file_name $l_current_file_name "
l_new_file_name_from_tag=$(echo "$l_file_path_with_match_tag" | egrep -o ">.*<" | sed "s/[><]//g" | head -1 )
l_new_file_name="${l_new_file_name_from_tag}${l_html_ext}"
l_new_file_path="$l_files_path/$l_new_file_name"
#echo "$l_new_file_path $l_new_file_path "
#echo "$l_new_file_name $l_new_file_name "
if [[ "$l_prev_file_path" == "$l_current_file_path" ]]; then
echo "$l_proc_name ERROR: myID tag is not unique for $l_current_file_path, skipping second renaming " >&2
let l_proc_exit_code+=1
continue
fi
if ! [[ -f "$l_new_file_path" ]]; then
if mv "$l_current_file_path" "$l_new_file_path" ; then
echo "$l_proc_name SUCCESS: renamed $l_current_file_path to $l_new_file_path"
else
echo "$l_proc_name ERROR: cannot move $l_current_file_path to $l_new_file_path" >&2
let l_proc_exit_code+=1
fi
else
if [[ "$l_current_file_name" == "$l_new_file_name" ]]; then
echo "$l_proc_name Warning: File has been already renamed: $l_current_file_name, skipping"
else
echo "$l_proc_name Warning: File with such name already exists: $l_current_file_name, skipping" >&2
let l_proc_exit_code+=1
fi
fi
l_prev_file_path=$l_current_file_path
done <<< $l_matched_files
return $l_proc_exit_code
}
# create test files
rm *.html
echo '<div id="myID" style="display:none">1_1</div>' > 1.html ;
echo '<div id="myID" style="display:none">1_2</div>' > 2.html ;
echo '<div id="myID" style="display:none">1_3</div>' > 3.html ;
echo '<div id="myID" style="display:none">1_3_1</div>' >> 3.html ;
# run
fn_rename_html_files