Category Archives: operating system

notes on and related to umask

umask – set file mode creation mask #include <sys/types.h> #include <sys/stat.h> mode_t umask(mode_t mask); Binary Number ————–> Decimal Number Abstraction Decide the required result to decide the needed mask. Binary Number ——————-> Resultant Binary ANDing with mask

GNU coreutils: Sources of random data

script file contents #!/bin/bash get_seeded_random() { seed=”$1″ echo $seed openssl enc -aes-256-ctr -pass pass:”$seed” -nosalt \ /dev/null } shuf -i1-100 –random-source=<(get_seeded_random 45) using /dev/urandom $sudo shuf -i1-5 –random-source=/dev/urandom 1 2 4 3 5 $sudo shuf -i1-5 –random-source=/dev/urandom 3 4 5 1 2 $sudo shuf -i1-5 –random-source=/dev/urandom 4 5 2 1 3 $sudo shuf -i1-5 –random-source=/dev/urandom …

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What if a user or group name is a string of digits?

root>useradd 1991 root>mkdir /home/1991 root>chown 1991.1991 /home/1991/ root>passwd 1991 Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully root>login 1991 Password: The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY …

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