git remote update origin --prune

man git-remote

git clean -Xdf

man git-clean man gitignore

## total number (in all branches)
git rev-list --all | wc -l
## number per committer
git shortlog -s -n --all

man git-rev-parse man git-shortlog

gcc -dM -E -x c /dev/null
g++ -dM -E -x c /dev/null
clang -dM -E -x c /dev/null
clang++ -dM -E -x c /dev/null

# certificate has PEM format (Pretty Enhanced Mail)
openssl x509 -in cert-file.pem -text -noout -fingerprint
# certificate has DER format (Distinguished Encoding Rules)
openssl x509 -inform der -in cert-file.cer -text -noout -fingerprint

man x509

openssl rsa -in privkey.pem -text -noout

man rsa

openssl req -in csr.pem -noout -text

man req

openssl pkcs12 -in yourP12File.pfx -clcerts -nokeys -out publicCert.pem
openssl pkcs12 -in yourP12File.pfx -nocerts -out privateKey.pem

man pkcs12

openssl genrsa -out privKey.pem
openssl req -new -x509 -key privKey.pem -out cert.pem

man genrsa man req

## with AES-NI (if available)
openssl speed -evp aes-256-cbc
## without AES-NI
OPENSSL_ia32cap="~0x200000200000000" openssl speed -evp aes-256-cbc
## multithread
openssl speed -multi 2 -evp aes-256-cbc

man speed

openssl asn1parse -in someCertOrKeyOrOther.pem

man asn1parse

curl test.schrimpe.de -x <[protocol://][user:password@]proxyhost[:port]> | w3m -dump -T text/html
# for Squid running on localhost that's:
curl test.schrimpe.de -x 127.0.0.1:3128 | w3m -dump -T text/html

man curl

curl https://test.schrimpe.de/ -w %{time_connect}:%{time_starttransfer}:%{time_total}

man curl

nc -w3 -z 192.168.0.1 80 ## return code zero on success

man nc

dig somehostname.local @224.0.0.251 -p 5353

man dig

## obtain the root keys first
drill -S -k /usr/local/etc/unbound/root.key kuehrmann.de
## if your resolver does not support DNSSEC use e.g. Quad9
drill -S -k /usr/local/etc/unbound/root.key kuehrmann.de @9.9.9.9

dig www.dnssec-failed.org

nmap -p- somehost.example.com

man nmap

find . -name "*.cpp" -print0 | xargs -0 wc -l

find . -type l ! -exec test -e {} \; -print

# create checksums of directory tree
rhash -r --md5 /backups/ > /tmp/backups.md5
rhash -r --crc32 /backups/ > /tmp/backups.sfv
# check one file containing MD5 hashes
rhash -c /tmp/backups.md5
# check all SFV, MD5 and SHA-256 files in directory tree
rhash -cr --crc-accept=sfv,md5,sha256 /tmp/directory/

man rhash

touch -a -m -t 202612180130.09 fileName.ext
## -a = accessed
## -m = modified
## -t = timestamp - use [[CC]YY]MMDDhhmm[.ss] time format

man touch

## create a 100 GiB sparse file
truncate -s 100G fileName.ext
## copy sparse files (works also from/to block devices; 4k should match the block size used within you sparse file)
dd if=inputSparse.ext of=outputSparse.ext bs=4096 conv=sparse

man truncate man dd

file -s /dev/sd*

## from a local disk send compressed image to remote host
dd if=/dev/sda bs=1048576 | pv | lz4 | ssh user@dest.example.com "dd of=/backup/basil-sda.img.lz4"
## to a local disk receive compressed image from remote host
ssh user@src.example.com "cat /backup/basil-sda.img.lz4" | lz4cat | pv | dd of=/dev/sda bs=1048576

convert big_input.tif -resize 256x256 small_output.png

man convert man ImageMagick

## prettify XML (proper indentation)
xmllint --format input_ugly.xml > output_pretty.xml
## uglify XML (remove unnecessary whitespace)
xmllint --noblanks input_pretty.xml > output_ugly.xml

xxd -i someFile.bin

man xxd

## with BSD date
date -r 1523210382
## with GNU date
date -d @1523210382

man date man date

## create named session using the terminal emulator "screen"
screen -dMS some_session_name /usr/bin/command command_args
## show PID of the "screen" session
screen -lsS some_session_name | awk '/\.some_session_name\t/ {print $1}' | cut -d. -f1
## attach to the session
screen -rS some_session_name

pgrep -P 56789

## show the current history
history
## determine the entry number, in this example the desired entry was #501
history -d 501

unset HISTFILE