Small snippets worth sharing: A collection of tricks to solve common problems

echo -n 'var inline = 1;' > /tmp/foobar
sha256sum /tmp/foobar | cut -d " " -f 1 | xxd -r -p | base64 

guix environment --ad-hoc icedtea:jdk -- \
  bash -c 'ssh kav freenet/run.sh stop; \
    ./gradlew --no-daemon clean build -x test && \
    for i in freenet.jar freenet.jar.new; do \
      scp build/libs/freenet.jar kav:freenet/$i; \
    done; \
    ssh kav freenet/run.sh start'

# start ~/path/to/source/branch-7.9/src/path/to/folder
cd $(echo $PWD | sed s/7.9/master/)
# now at ~/path/to/source/branch-master/src/path/to/folder

# better bash history handling
# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
export HISTSIZE=100000
export HISTFILESIZE=1000000
# append to the history file, don't overwrite it
shopt -s histappend
# don't put duplicate lines or lines starting with space in the history.
# See bash(1) for more options
export HISTCONTROL=ignoredups:erasedups
# update the history with every command, not only at exit
export PROMPT_COMMAND="history -a;$PROMPT_COMMAND"

# check the window size after each command and, if necessary,
# update the values of LINES and COLUMNS.
shopt -s checkwinsize

# If set, the pattern "**" used in a pathname expansion context will
# match all files and zero or more directories and subdirectories.
shopt -s globstar

(cond ((false-if-exception (resolve-interface '(ice-9 readline)))
       =>
       (lambda (module)
         ;; Enable completion and input history at the REPL.
         ((module-ref module 'activate-readline))))
      (else
       (display "Consider installing the 'guile-readline' package for
convenient interactive line editing and input history.\n\n")))

      (unless (getenv "INSIDE_EMACS")
        (cond ((false-if-exception (resolve-interface '(ice-9 colorized)))
               =>
               (lambda (module)
                 ;; Enable completion and input history at the REPL.
                 ((module-ref module 'activate-colorized))))
              (else
               (display "Consider installing the 'guile-colorized' package
for a colorful Guile experience.\n\n"))))

#!/run/current-system/profile/bin/bash

# This script makes a scanned image suitable (=small enough) for
# sending as homework assignment by replacing almost-white pixes from
# scans by white pixels and then running pngquant

# thanks for the urldecoder goes to to https://stackoverflow.com/a/37840948
# license: cc by-sa (as this is stackoverflow)
urldecode() { : "${*//+/ }"; echo -e "${_//%/\\x}"; }
base="$(echo $(urldecode "$NAUTILUS_SCRIPT_CURRENT_URI") | cut -d / -f3-)"
while [ ! -z "$1" -a ! -e "$base/$1" ]; do shift; done
filename="$base/$1"

if [ -f "$filename" ] && [[ x"$(file -b --mime-type "$filename" | sed s,/.*,,)" = x'image' ]]; then
    COLORFILE="${filename%.*}-colors.${filename#*.}"
    if [ -f "${COLORFILE}" ]; then
       zenity --error --width 400 \
              --text "Temporary file ${COLORFILE} already exists, not overwriting" \
              --title "temp file exists: ${COLORFILE}";
    else
        convert "${filename}" -contrast-stretch 1%x80% "${COLORFILE}"
        pngquant --skip-if-larger --strip --speed 1 "${COLORFILE}" || zenity --error --width 400 \
                 --text "running pngquant on ${COLORFILE} failed";
    fi
else
    zenity --error --width 400 \
                   --text "image optimization needs an image file, but \n${filename}\n is not an image file.\n\nIts mime type is $(file -b --mime-type "$filename")" \
                   --title "not an image: ${filename}"
fi

cp logs/access_log_2021*.gz /tmp/
cd /tmp/
gunzip access_log_2021-0*
cat access_log* > aggregated_log.log
goaccess --all-static-files --ignore-crawlers -f aggregated_log.log

goaccess --date-format='%d/%b/%Y' \
         --time-format='%H:%M:%S' \
         --log-format='%h %^[%d:%t %^] "%r" %s %b "%R" "%u"' \
         --max-items=99999999 --all-static-files --ignore-crawlers \
         -f /tmp/aggregated_log.log \
         -o /tmp/agg.csv