Skip to content

Tools & Utils

Duplicate files

Find: find ~/Videos/ -type f -print0 | xargs -0 -P 16 -L 1 md5sum | sort | uniq -D -w 32

Delete duplicates:

  1. Save the output of the above command in a file (db.txt), and then

  2. Execute this:

    nano ~/remove-duplicates.fish
    #!/usr/bin/env fish

set db_path $argv[1]

if test -z $db_path
    echo "Please provide the path to the file that contains the MD5 hashes and file paths."
    exit 1
end

set prev_seen_hash ""

function maybe_delete_file --argument-names file
    if test -z $DELETE_DUPLICATES_DRY_RUN
        echo "Deleting \"$file\"..."
        set fish_trace 1
        rm -f "$file"
        set fish_trace 0
    else
        echo "Would delete (dry-run): $argv"
    end
end

cat $db_path | while read -l line
    set -l components (string split " " -- $line)
    set curr_hash $components[1]
    set curr_file $components[3..-1]

    if test "$prev_seen_hash" = "$curr_hash"
        maybe_delete_file $curr_file
    end
    set prev_seen_hash $curr_hash
end

Compression

A directory: 

# Compress:
tar -I "zstd --threads 30 --ultra -19 --memory 8192" -cf scripts.tar.zst scripts/

# Decompress:
tar --zstd -xf scripts.tar.zst

A single file:

# Compress:
zstd --compress --threads 30 --ultra -19 --memory 8192 -o file.txt.zstd file.txt

# Decompress:
zstd --decompress file.txt.zstd

A couple of observations:

  • zstd uses cores up to the compression level of 19 (including).
  • --ultra -22 gives the best compression

Alternatives

Add clang alternatives:

1
2
3
4
5
sudo update-alternatives                                             \
      --install /usr/bin/clang   clang   /usr/bin/clang-3.8     50   \
      --slave   /usr/bin/clang++ clang++ /usr/bin/clang++-3.8        \
      --slave   /usr/bin/lldb    lldb    /usr/bin/lldb-3.8           \
      --slave   /usr/bin/llvm-symbolizer llvm-symbolizer /usr/bin/llvm-symbolizer-3.8

Display info about given alternative:

1
2
3
4
5
6
7
update-alternatives --display clang
clang - auto mode
  link currently points to /usr/bin/clang-3.5
/usr/bin/clang-3.5 - priority 50
  slave clang++: /usr/bin/clang++-3.5
  slave lldb: /usr/bin/lldb-3.5
Current 'best' version is '/usr/bin/clang-3.5'.

Permissions

Restore default permissions (x for dirs, no x for files):

chmod -R u=rwX,g=rwX,o=rwX ${HOME}

X permission: execute/search only if the file is a directory or already has execute permission for some user.

1
2
find ${HOME} -type f -exec chmod 0664 {} +
find ${HOME} -type d -exec chmod 0775 {} +

Note, unlike X, it will remove x permission from files.

setfacl -dm u::rws,g::rwx,o::rx /dir/

initrd.img

  • Extract initrd.img: unmkinitramfs /boot/initrd.img-5.15.0-30-generic ../new-init/

Hash of a directory

find ./ -type f -exec sha256sum {} + | sha256sum

Mouse scroll speed

See askubuntu.