Linux

Explain shell — help text for each command line argument.

full-upgrade performs the function of upgrade but may also remove installed packages if that is required

sudo apt update
sudo apt full-upgrade

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Show the path of (shell) commands.

which firefox
whereis firefox

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mkdir -p creates parent directories if necessary

mkdir -p path/to/directory/{file1,file2,file3}

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Ctrl+R      #reverse-i-search
date -u     #UTC data

info command
command --help
xdg-open .
xdg-open http://codebicycle.com

nslookup -debug rogifts.com. 8.8.8.8
dig rogifts.com
traceroute -w 2 rogifts.com

grep --color=always "search string" * | less -R
less -M     # progress indicator
/           # search in man pages (n next occurrence, p)

Process tree

pstree

Equivalent?

echo $(which python)
echo `which python`

Globing (glob patterns)

mv *.txt textfiles/

Auto-complete filenames

Alt + /

Shell expand

$HOME Ctrl + Alt + E

Command substitution

$(command)
touch file-$(date +%y-%m-%d)

This should tell us if any of the intermediate directories are blocking the www-data user from opening the socket.

sudo -u ww-data ls /var/opt/gitlab/gitlab-workhorse/socket

Batch rename files

# rename [ -v ] [ -n ] [ -f ] perlexpr [ files ]
# test run
rename -n ’s/\.htm$/\.html/’ *.htm
# verbose rename
rename -v ’s/\.htm$/\.html/’ *.htm