Ranger : do not try to display large files (preview)

I am using Ranger as a file explorer, and by the way it’s great…

I have an issue because Ranger can display a preview of the file currently
selected. Which is quite useful but becomes problematic for large files.
Indeed, for large files, it takes a lot of time and ressources to do create a
preview.

My question is : is there a way to set the maximal size for which Ranger won’t
try to display a preview ?

Asked By: PinkFloyd

||

I found the solution, at least for text files, the problem was in the
highlighting… Ranger was trying to highlight long files… the workaround I
found is shown in the following excerpt of ~/.config/ranger/scope.sh

#!/usr/bin/env sh

path="$1"    # Full path of the selected file
width="$2"   # Width of the preview pane (number of fitting characters)
height="$3"  # Height of the preview pane (number of fitting characters)
maxln=54    # Stop after $maxln lines.  Can be used like ls | head -n $maxln

# Find out something about the file:
mimetype=$(file --mime-type -Lb "$path")
extension=${path##*.}

try() { output=$(eval '"$@"'); }
dump() { echo "$output"; }
trim() { head -n "$maxln"; }
hl() { command head -n "$maxln" "$path" | highlight --syntax="$extension" --out-format=ansi; test $? = 0 -o $? = 141; }

case "$mimetype" in
    # Syntax highlight for text files:
    text/* | */xml)
        try hl && { dump | trim; exit 5; } || exit 2;;
esac
exit 1

The idea, it to select only the first lines of the textfile and then call
highligh only on that portion.

Answered By: PinkFloyd

You can include commands, in some parts of your scope.sh, to check for file size.

First, add new function (paste code above handle_extension() in scope.sh):

drop_bigsize() {
    # 51200 == 50 MB * 1024
    # change this number for different sizes
    if [[ `du "${FILE_PATH}" | cut -f1` -gt 51200 ]]; then
        echo '----- TOO BIG FILE -----'
        exit 0
    fi
}

Second, call that function somewhere in scope.sh.
For example, the code below will prevent from previewing any files with size bigger than 50MB (its the last few lines from scope.sh):

...
MIMETYPE="$( file --dereference --brief --mime-type -- "${FILE_PATH}" )"

### start of new block ###
drop_bigsize
### end of new block ###

if [[ "${PV_IMAGE_ENABLED}" == 'True' ]]; then
    handle_image "${MIMETYPE}"
fi

handle_extension
handle_mime "${MIMETYPE}"
handle_fallback

exit 1

To do such stuff with some specific file types, e.g. for some archives, you would need to place the same block of code in different part of your scope.sh:

...
handle_extension() {
    case "${FILE_EXTENSION_LOWER}" in
        # Archive
        a|ace|alz|arc|arj|bz|bz2|cab|cpio|deb|gz|jar|lha|lz|lzh|lzma|lzo|
        rpm|rz|t7z|tar|tbz|tbz2|tgz|tlz|txz|tZ|tzo|war|xpi|xz|Z|zip)
            ### start of new block ###
            drop_bigsize
            ### end of new block ###
            atool --list -- "${FILE_PATH}" && exit 5
            bsdtar --list --file "${FILE_PATH}" && exit 5
            exit 1;;
        rar)
            # Avoid password prompt by providing empty password
            unrar lt -p- -- "${FILE_PATH}" && exit 5
            exit 1;;
...
Answered By: banderlog013
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