selfh.st: Command Corner

• There are some extremely useful commands here, & I just wanted to have them noted down somewhere.

tr -dc A-Za-z0-9_ < /dev/urandom | head -c 16 | xargs

• Use tr -dc A-Za-z0-9_ < /dev/urandom | head -c 16 | xargs to quickly generate a password from the command line (create a bash alias for quick reference in the future):

$ tr -dc A-Za-z0-9_ < /dev/urandom | head -c 16 | xargs
nfZY12B8v9ppdayQ

ls | wc -l

• Use ls | wc -l to quickly count the number of files & folders in the current directory:

$ ls | wc -l
8

for i in *; do test -d $i && du -sh $i; done

` Use for i in *; do test -d $i && du -sh $i; done to output a list of directories in the current folder and their sizes (skipping files and subdirectories):

$ for i in *; do test -d $i && du -sh $i; done
806M	Development
...
2.1G	Docker
56K	Documents
44K	snap
31G	Syncthing

ls -lt

• Use ls -lt from the command line to quickly list files and directories by last modified time:

ls -t

• This will do the same as the above, except just lists the folder in order of last modified time, not including any extra information (permissions, size, date, etc)

history > commands.txt

• Use history > commands.txt to save the terminal’s command history directly to a file: