Commands using echo (1,545)

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Ctrl+S Ctrl+Q terminal output lock and unlock
These are simple shortcuts to pause and continue terminal output, works in most terminals and screen multiplexers like screen. You can use it to catch something if things change too fast, and scroll with Shift + PgUp PgDown. On linux console ScrollLock can also be used.

Determine if a command is in your $PATH using POSIX
it is generally advised to avoid using which(1) whenever possible. which(1) is usually a csh(1) script, or sometimes a compiled binary. It's output is highly variable from operating system to operating system, so platform independent scripts could become quite complicated with the logic. On HP-UX 10.20, for example, it prints "no bash in /path /path /path ..."; on OpenBSD 4.1, it prints "bash: Command not found."; on Debian (3.1 through 5.0 at least) and SuSE, it prints nothing at all; on Red Hat 5.2, it prints "which: no bash in (/path:/path:...)"; on Red Hat 6.2, it writes the same message, but on standard error instead of standard output; and on Gentoo, it writes something on stderr. And given all these differences, it's still variable based on your shell. This is why POSIX is king. See http://mywiki.wooledge.org/BashFAQ/081 for more ways on avoiding which(1).

sort a JSON blob
For situations where you keep JSON in a VCS and you want your diffs to be sane, such as within a Chef configuration repo.

Delete leading whitespace from the start of each line

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

prints the parameter you used on the previous command

Show a passive popup in KDE
Display a passive popup during seconds. Additionnaly, --title can be used to set the title of the popup. This is a nice way to communicate with a desktop user of a machine you have an SSH access on : DISPLAY=:0 sudo -u $user -H kdialog --passivepopup "Hello you" 10 --title "cli IM"

Show a config file without comments

Create a new file

check open ports without netstat or lsof


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