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Extracting the second word from a string variable

https://unix.stackexchange.com/questions/174037/extracting-the-second-word-from-a-string-variable

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pstree command usage example

$pidof systemd 1461 1059 $pstree 1461 systemd─┬─(sd-pam) ├─at-spi-bus-laun─┬─dbus-daemon │ └─3*[{at-spi-bus-laun}] ├─at-spi2-registr───2*[{at-spi2-registr}] ├─dbus-daemon ├─dconf-service───2*[{dconf-service}] ├─evolution-addre─┬─evolution-addre───5*[{evolution-addre}] │ └─4*[{evolution-addre}] ├─evolution-calen─┬─evolution-calen───9*[{evolution-calen}] │ └─4*[{evolution-calen}] ├─evolution-sourc───3*[{evolution-sourc}] ├─gnome-shell-cal───5*[{gnome-shell-cal}] ├─gnome-terminal-─┬─bash───pstree │ └─3*[{gnome-terminal-}] ├─goa-daemon───4*[{goa-daemon}] ├─goa-identity-se───3*[{goa-identity-se}] ├─gvfs-afc-volume───3*[{gvfs-afc-volume}] ├─gvfs-goa-volume───2*[{gvfs-goa-volume}] ├─gvfs-gphoto2-vo───2*[{gvfs-gphoto2-vo}] ├─gvfs-mtp-volume───2*[{gvfs-mtp-volume}] ├─gvfs-udisks2-vo───2*[{gvfs-udisks2-vo}] ├─gvfsd───2*[{gvfsd}] ├─gvfsd-fuse───5*[{gvfsd-fuse}] ├─gvfsd-metadata───2*[{gvfsd-metadata}] ├─mission-control───3*[{mission-control}] ├─pulseaudio───2*[{pulseaudio}] └─tracker-store───7*[{tracker-store}] $pstree 1059 systemd─┬─(sd-pam) ├─at-spi-bus-laun─┬─dbus-daemon │ └─3*[{at-spi-bus-laun}] ├─at-spi2-registr───2*[{at-spi2-registr}] ├─dbus-daemon └─pulseaudio───2*[{pulseaudio}] $ $pstree `pidof systemd | awk ‘{print $2}’` systemd─┬─(sd-pam) …

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How do I get the parent process ID of a given child process?

https://askubuntu.com/questions/153976/how-do-i-get-the-parent-process-id-of-a-given-child-process https://superuser.com/questions/150117/how-to-get-parent-pid-of-a-given-process-in-gnu-linux-from-command-line/544696#544696

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perf: Linux profiling with performance counters

https://perf.wiki.kernel.org/index.php/Tutorial#Attaching_to_a_running_process

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A bit field is a data structure used in computer programming

https://en.wikipedia.org/wiki/Bit_field

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Search for a pattern at the beginning of a line using grep

$ps -e “kworker$” error: unknown sort specifier Usage: ps [options] Try ‘ps –help ‘ or ‘ps –help ‘ for additional help text. For more details see ps(1). $ps -ef | grep “^daemon” daemon 639 1 0 May04 ? 00:00:00 /usr/sbin/atd -f $ps -ef | grep “^rtkit” rtkit 1245 1 0 May04 ? 00:00:00 /usr/lib/rtkit/rtkit-daemon $ps …

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why does “exit status 0” mean success?

https://www.quora.com/in/Why-does-%E2%80%9Cexit-status-0%E2%80%9D-mean-success

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tinkering with trap and exit commands

$echo $? 0 $echo $? 0 $exit 10 | tee solve.txt $cat solve.txt $rm solve.txt $exit 10 | echo $? 0 $exit -1 | echo $? 0 $exit -1 | echo $? 0 $false | true $echo $? 0 $false $echo $? 1 $true $echo $? 0 $exit 5 | tee var=$? $file var\=0 var=0: …

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Indicate how each name would be interpreted if used as a command name

$type -a locate locate is /usr/bin/locate $type -a ls ls is aliased to `ls –color=auto’ ls is /bin/ls $type -t ls alias $type -t locate file $type -t /dev/urandom $type -t /dev/sda1 $type -t urandom $type -t sda1 $type -t type builtin $type -t shuf file $type -t bash file $type -t proc $type -t …

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Non-deterministic Algorithms

https://cs.nyu.edu/courses/spring03/G22.2560-001/nondet.html

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