title: Bashcat << EOF > file.txt
The current working directory is $PWD.
You are logged in as $(whoami).
EOF
Suppose we have two files: packages.fedora and packages.
packages.fedora:
autossh
bash-completion
bat
bc
borgmatic
bzip2
cmake
curl
diff-so-fancy
diffutils
dnf-plugins-core
packages:
bash-completion
bc
bzip2
curl
diffutils
dnf-plugins-core
To plain-print the lines that exist in packages.fedora but do not exist packages:
comm -23 <(sort packages.fedora) <(sort packages)
Output:
autossh
bat
borgmatic
cmake
diff-so-fancy
comm command compares two sorted files line by line.-23 flag is shorthand for -2 and -3.-2 : suppress column 2 (lines unique to packages)-3 : suppress column 3 (lines that appear in both files)split -l 60 bigfile.txt prefix-
while read line; do
echo "$line";
done </path/to/file.txt
cat urls.html | grep -Eo "(http|https)://[a-zA-Z0-9./?=_%:-]*"
grep -E: egrepgrep -o: only output what has been grepped(http|https): either http OR httpsa-zA-Z0-9: match all lowercase, uppercase, and digits.: match period/: match slash?: match ?=: match =_: match underscore%: match percent:: match colon-: match dash*: repeat the [...] group any number of timesps aux output followed by each grepped lineTo find all cron processes with ps aux.
ps aux | awk 'NR<2{print $0;next}{print $0 | grep "cron"}' | grep -v "awk"
ps aux : equivalent to ps -aux. -a displays info about other users processes besides to current user. -u displays info associated with keywords user, pid, %cpu, %mem, vsz, rss, tt, state, start, time, and command. -x includes processes which do not have a controlling terminal. See man 1 ps.awk 'NR<2{print $0;next}{print $0 | "grep cron"}' | grep -v "awk" : For number of input records (NR) less than 2, print the input record ($0), go to the next input record and repeat the {print $0} pattern until the end is reached, then execute the END rule. The End rule in this case is {print $0 | "grep cron"}, it prints the remaining input records after piping them through the "grep cron" command. This allows printing the first line of the ps aux output, which consists of the column labels, and filters out everything besides what you want to grep for (e.g. "cron" processes).grep -v "awk" : avoids printing the line containing this command.