# convert to base64:
base64 -w0 /path/to/file | pbcopy  # or `xclip`, `xsel` for Linux
# transfer the text using your chosen method, the recipient should paste the plaintext in a file:
base64 -d /path/to/encoded/file > /path/to/decoded/file

# Some basic redirection
% ls -l  # stdout is printed to the terminal
% ls -l > /tmp/ls-l.txt  # stdout is redirected to a file
% > /tmp/ls-la.txt ls -la  # stdout is redirected to a file (order doesn't matter)
% ls -M  # stderr is printed to the terminal
ls: invalid option -- 'M'
Try 'ls --help' for more information.
% ls -M 2>&1 | grep 'invalid'  # stderr is redirected to stdout
ls: invalid option -- 'M'
% ls -M 2> /dev/null  # stderr is sent to a blackhole (i.e. ignore all errors)

# Some intermediate redirection
% for i in {1..5}; do date >> /tmp/timestamps; sleep 5; done  # append output to file
% for i in {1..5}; do date | tee /tmp/timestamps; sleep 1; done  # split stdout to file and terminal
% brew list --formula -1 > /tmp/brew-list  # output a list of installed packages
% while read -r formula; do brew info $formula; done < /tmp/brew-list  # stdin is a file
% while read -r formula; do brew info $formula; done <<< "$(brew list --formula -1)"  # stdin is a command
% docker image prune -f > /dev/null 2>&1  # redirect stderr to stdout and redirect stdout to /dev/null (i.e. ignore everthing)

# Using redirection instead of pipes
% tr ' ' '\n' <<< "$(id -Gn)"
% sed 's/Fri/Friday/' < /tmp/timestamps

# Using process substitution
% diff <(sort file1) <(sort file2)  # the output of a command appears as a file

# The `find` command is the default go-to included in Unix systems:
% touch file{1..5} && mkdir dir{6..9} && mkdir -p dir10/folder{1..5}

% find . -type f
./file3
./file4
./file5
./file2
./file1

% find . -type d
.
./dir10
./dir10/folder5
./dir10/folder2
./dir10/folder3
./dir10/folder4
./dir10/folder1
./dir6
./dir8
./dir9
./dir7

# Restict searching depth with -mindepth and -maxdepth:
% find . -mindepth 1 -maxdepth 1 -type d
./dir10
./dir6
./dir8
./dir9
./dir7

# Perform operations on the results:
% brew info coreutils --json > coreutils.json && brew info git --json > git.json
% find . -type f -name '*.json' -exec jq '.[]|.desc' {} \;
"GNU File, Shell, and Text utilities"
"Distributed revision control system"

# Delete matching results:
% find . -type f -name '*.json' -delete

# Examples showing how to split the command and the arguments:
% parallel echo {} ::: hello world
hello
world

% parallel echo {1} {2} ::: alpha beta ::: one two
alpha one
alpha two
beta one
beta two

# Convert an audio file simultaneously to multiple formats:
parallel ffmpeg ~/Audio/file.flac ~/Audio/file.{} ::: ogg m4a opus

# Simultaneously convert multiple tab separated files to csv files:
parallel "tr '\t' ',' < {} > {.}.csv" ::: *.tsv

# Create individual directory archives simultaneously:
% ls
dir1 dir2 dir3
% find . -maxdepth 1 -mindepth 1 -type d | parallel "tar -czf {.}.tar.gz {}"
% ls
dir1 dir1.tar.gz dir2 dir2.tar.gz dir3 dir3.tar.gz

# Create some files
% for num in {1..4}; do echo "file no. ${num}" > "/tmp/file${num}"; done

# Select files to print
% cat /tmp/file{1,3}
file no. 1
file no. 3

# Select a range of files to print:
% cat /tmp/file{2..4}
file no. 2
file no. 3
file no. 4

# Make a copy of a file with a new extension:
% cp /tmp/file1{,.txt}
% ls -1 /tmp/
file1
file1.txt
file2
file3
file4

# Create multiple directories
% mkdir -p /tmp/{alpha,beta}/{one,two,three}
% tree -dL 2 /tmp
/tmp
├── alpha
│   ├── one
│   ├── three
│   └── two
└── beta
    ├── one
    ├── three
    └── two