Omassh

Snippets

S lists the scripts worth keeping, so a command you run often is typed once rather than remembered. n, e and d make, change and remove them. The row beside a name shows the command itself where there is one line of it, and the size where there is more.

Writing one

A one-line script is typed into the form. Anything longer goes to your editor on ctrl+e — $VISUAL first, then $EDITOR, then vi — and comes back with whatever you saved. Omassh does not grow a text area for this, for the reason it does not implement SSH: there is an editor on the machine already, and it is better than the one that would be written here. A script too long for its field reads 4 lines — ctrl+e to edit, and the field stops taking keystrokes, so a description typed in the wrong place can never be saved as the script.

Running one

↵ on a snippet opens a screen showing the whole script and the ways of saying where to run it:

• this host — the one selected in the host list
• this group — every host the list is showing; under a search it offers the matches instead, and calls them that
• pick hosts… — any set at all, ticked with space, where a chooses all or none

Nothing runs until you confirm on that screen, with y or a second ↵. That step is not ceremony: a long snippet is listed by its size, so a single ↵ would be running something you cannot see on machines you have to be right about.

Results fill in as they arrive, one row per host, each carrying the last line that host said, and ↵ on a row opens what it said in full. esc stops the run and keeps what has already come back, because the hosts that did finish are worth reading, and closing the screen would take them away in the same moment. A second esc leaves without waiting, for a run whose results are not coming: killing ssh does not close a pipe that a background process on the host is still holding.

Four hosts run at a time. A probe is a TCP connection and nothing else, but a run is a whole ssh session plus whatever the script does at the far end, and thirty simultaneous package upgrades is not a thing to start by accident. Hosts past the limit are shown as queued rather than running, because they are.

A run has no terminal. It goes through the same unattended path SFTP does, so sudo asking for a password fails at once instead of waiting on a keyboard that is not there — which is the right answer, since waiting is the one thing a connection nobody is watching must never do. A password credential still works, because the keychain answers rather than a person. What a run cannot do is anything interactive, and that is what pasting is for.

Pasting one

p pastes the snippet into the session in the pane instead, and stops there. It arrives as a paste rather than as typing, which a shell that understands bracketed paste holds in its edit buffer for you to read, change and run yourself. One that does not understand it — macOS ships a bash whose readline predates the idea — runs each line as it arrives. Which of those happened cannot be known from here: the mode belongs to the shell at the far end, and with tmux in between, it is tmux’s own that reaches Omassh. So nothing is claimed. A one-line snippet always waits, because what would run it is the trailing newline Omassh takes off; a longer one says to go and look, next to the pane it has just put in front of you.

In an export

omassh export carries a snippet’s script exactly as written, which is also the warning: a password belongs in a credential, where the export does not carry it, and never in a script, where it does.

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