scope.sh

#!/usr/bin/env sh
# ranger supports enhanced previews.  If the option "use_preview_script"
# is set to True and this file exists, this script will be called and its
# output is displayed in ranger.  ANSI color codes are supported.

# NOTES: This script is considered a configuration file.  If you upgrade
# ranger, it will be left untouched. (You must update it yourself.)
# Also, ranger disables STDIN here, so interactive scripts won't work properly

# Meanings of exit codes:
# code | meaning    | action of ranger
# -----+------------+-------------------------------------------
# 0    | success    | success. display stdout as preview
# 1    | no preview | failure. display no preview at all
# 2    | plain text | display the plain content of the file
# 3    | fix width  | success. Don't reload when width changes
# 4    | fix height | success. Don't reload when height changes
# 5    | fix both   | success. Don't ever reload

# Meaningful aliases for arguments:
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=200    # 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=$(echo "${path##*.}" | tr "[:upper:]" "[:lower:]")

# Functions:
# runs a command and saves its output into $output.  Useful if you need
# the return value AND want to use the output in a pipe
try() { output=$(eval '"$@"'); }

# writes the output of the previously used "try" command
dump() { echo "$output"; }

# a common post-processing function used after most commands
trim() { head -n "$maxln"; }

# wraps highlight to treat exit code 141 (killed by SIGPIPE) as success
highlight() { command highlight "$@"; test $? = 0 -o $? = 141; }

case "$extension" in
    # Archive extensions:
    7z|a|ace|alz|arc|arj|bz|bz2|cab|cpio|deb|gz|jar|lha|lz|lzh|lzma|lzo|\
    rpm|rz|t7z|tar|tbz|tbz2|tgz|tlz|txz|tZ|tzo|war|xpi|xz|Z|zip)
        try als "$path" && { dump | trim; exit 0; }
        try acat "$path" && { dump | trim; exit 3; }
        try bsdtar -lf "$path" && { dump | trim; exit 0; }
        exit 1;;
    rar)
        try unrar -p- lt "$path" && { dump | trim; exit 0; } || exit 1;;
    # PDF documents:
    pdf)
        try pdftotext -l 10 -nopgbrk -q "$path" - && \
            { dump | trim | fmt -s -w $width; exit 0; } || exit 1;;
    # BitTorrent Files
    torrent)
        try transmission-show "$path" && { dump | trim; exit 5; } || exit 1;;
    # HTML Pages:
    htm|html|xhtml)
        try w3m    -dump "$path" && { dump | trim | fmt -s -w $width; exit 4; }
        try lynx   -dump "$path" && { dump | trim | fmt -s -w $width; exit 4; }
        try elinks -dump "$path" && { dump | trim | fmt -s -w $width; exit 4; }
        ;; # fall back to highlight/cat if the text browsers fail
esac

case "$mimetype" in
    # Syntax highlight for text files:
    text/* | */xml)
        try highlight --out-format=ansi "$path" && { dump | trim; exit 5; } || exit 2;;
    # Ascii-previews of images:
    image/*)
        img2txt --gamma=0.6 --width="$width" "$path" && exit 4 || exit 1;;
    # Display information about media files:
    video/* | audio/*)
        exiftool "$path" && exit 5
        # Use sed to remove spaces so the output fits into the narrow window
        try mediainfo "$path" && { dump | trim | sed 's/  \+:/: /;';  exit 5; } || exit 1;;
esac

exit 1