Running Commands¶

Exec opens an SSH session channel, requests remote execution, and collects standard output until the channel closes:

      r←c.Exec 'df -h /'
      r.rc
0
      ⎕←r.Data
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2       196G   58G  128G  32% /

Any number of Exec calls can share one connection; each opens its own channel:

      {(c.Exec ⍵).Data} 'whoami'
alice

What Data contains¶

r.Data is the command's complete standard output.

• Output that is valid UTF-8 is decoded to APL characters — including multi-byte text (é, →, CJK, …).
• Output that is not valid UTF-8 (e.g. cat of a binary file) is returned as byte-preserving characters: one character per byte, values 0–255. Recover the raw bytes with ⎕UCS r.Data.

Commands themselves are sent UTF-8 encoded, so non-ASCII arguments and filenames work:

      r←c.Exec 'ls ''döcs'''

Large outputs are fine — the client reassembles output spanning many SSH packets and replenishes the flow-control window automatically.

Exit status, stderr, and signals¶

Beyond Data, the Exec result carries how the command ended:

      z←c.Exec 'ls /etc/passwd /nope'
      z.(ExitStatus Data Stderr)
2  /etc/passwd  ls: cannot access '/nope': No such file or directory

Failure modes¶