¿Cómo funciona este complejo script de shell BASH?

El miembro de la comunidad de soporte de Apple, Linc Davis, desarrolló este comando para ayudar a diagnosticar problemas. La salida da una visión general del sistema y es muy similar al programa etrecheck . Pero, lo hace usando un solo comando. Deseo desglosar cómo funciona, ya que gran parte de la sintaxis utilizada no se puede encontrar en las páginas MAN. Nuevamente, este guión es propiedad de Linc Davis. Simplemente deseo entender cómo se ejecuta. Gracias de antemano.

clear; shopt -s extglob; Fb='%s\n\t(%s)\n'; Fm='\n%s:\n\n%s\n'; Fs='\n%s: %s\n'; PB="/usr/libexec/PlistBuddy -c Print"; Pm () { [[ "$o" ]] && o=$(sed 's/^/ /' <<< "$o") && printf "$Fm" "$1" "$o"; }; Pc () { o=$(egrep -v '^[[:blank:]]*($|#)' "$2"); Pm "$1"; }; Pp () { o=$($PB "$2" | awk -F'= ' \/$3'/{print $2}'); Pm "$1"; }; Ps () { o="${o##+( )}"; [[ "$o" -ne 0 ]] && printf "$Fs" "$1" "$o"; }; a=$(id | grep -w '80(admin)'); r=1; [[ "$a" ]] && { sudo true; r=$?; }; { [[ "$a" ]] || echo $'No admin access\n'; [[ "$a" && "$r" -ne 0 ]] && echo $'No root access\n'; system_profiler SPSoftwareDataType | sed '8!d;s/^ *//'; o=$(system_profiler SPDiagnosticsDataType | sed '5,6!d'); fgrep -q P <<< "$o" && o=; Pm "POST"; o=$(nvram boot-args | awk '{$1=""; print}'); Ps "boot-args"; o=$(df -m / | awk 'NR==2 {print $4}'); [[ $o -lt 5120 ]] && Ps "Free space (MiB)"; o=$(($(vm_stat | awk '/Pageo/{sub("\\.",""); print $2}')/256)); o=$((o>=1024?o:0)); Ps "Pageouts (MiB)"; s=( $(sar -u 1 10 | sed '$!d') ); [[ ${s[4]} -lt 90 ]] && o=$(printf 'User %s%%\t\tSystem %s%%' ${s[1]} ${s[3]}) || o=; Pm "Total CPU usage" && o=$(ps acrx -o comm,ruid,%cpu | sed '2!d'); Pm "Max %CPU by process (name, UID, %)"; o=$(kextstat -kl | grep -v com\\.apple | cut -c53- | cut -d\< -f1); Pm "Loaded extrinsic kernel extensions"; o=$(launchctl list | sed 1d | awk '!/0x|com\.apple|org\.(x|openbsd)|\.[0-9]+$/{print $3}'); Pm "Loaded extrinsic user agents"; o=$(launchctl getenv DYLD_INSERT_LIBRARIES); Pm "Inserted libraries"; for f in crontab fstab launchd.conf sysctl.conf; do Pc $f /etc/$f; done; Pc "hosts" <(sed '1,10d' /etc/hosts); Pc "User crontab" <(crontab -l); Pc "User launchd" ~/.launchd; o=$(find {,/u*/lo*}/e*/periodic -type f -mtime -10d); Pm "Modified periodic scripts"; Pp "Global login items" /L*/P*/loginw* Path; Pp "User login items" L*/P*/*loginit* Name; Pp "Safari extensions" L*/Saf*/*/E*.plist Bundle | sed 's/\..*$//;s/-[1-9]$//'; o=$(find ~ $TMPDIR.. \( -flags +sappnd,schg,uappnd,uchg -o ! -user $UID -o ! -perm -600 \) | wc -l); Ps "Restricted user files"; cd; o=$(find -L /S*/L*/E* {/,}L*/{A*d,Compon,Ex,In,Keyb,Mail/Bu,P*P,Qu,Scripti,Servi,Spo}* -type d -name Contents -prune | while read d; do ID=$($PB\ :CFBundleIdentifier "$d/Info.plist") || ID="No bundle ID"; egrep -qv "^com\.apple\.[^x]|Accusys|ArcMSR|ATTO|HDPro|HighPoint|driver\.stex|hp-fax|\.hpio|JMicron|microsoft\.MDI|print|SoftRAID" <<< $ID && printf "$Fb" "${d%/Contents}" "$ID"; done); Pm "Extrinsic loadable bundles"; o=$(find /u*/{,*/}lib -type f -exec sh -c 'file -b "$1" | grep -qw shared && ! codesign -v "$1"' {} {} \; -print); Pm "Unsigned shared libraries"; o=$(system_profiler SPFontsDataType | egrep "Valid: N|Duplicate: Y" | wc -l); Ps "Font problems"; for d in {/,}L*/{La,Priv,Sta}*; do o=$(ls -A "$d" | egrep -v '\.DS_Store|^com\.apple'); Pm "$d"; done; o=$(ls /L*/L*/Dia*/*.panic | wc -l); Ps "Panics"; o=$(ls /L*/L*/Dia*/*.c* | tail); Pm "System crash logs"; o=$(ls L*/L*/Dia* | tail); Pm "User crash logs"; [[ "$r" -eq 0 ]] && { o=$(sudo profiles -P); Pm "Profiles"; o=$(sudo launchctl list | sed 1d | awk '!/0x|com\.(apple|openssh|vix\.cron)|org\.(amav|apac|calendarse|cups|dove|isc|ntp|post[fg]|x)/{print $3}'); Pm "Loaded extrinsic daemons"; o=$(sudo defaults read com.apple.loginwindow LoginHook); Pm "Login hook"; Pc "Root crontab" <(sudo crontab -l);}; o=$(syslog -F bsd -k Sender kernel -k Message CReq 'GPU |hfs: Ru|I/O e|n Cause: -|NVDA\(|pagin|timed? ?o' | tail -n25 | awk '/:/{$4=""; $5=""; print}'); Pm "Kernel messages"; } 2> /dev/null | pbcopy; exit