Table of Contents
Control S Control Q Commands To Manipulate Flow On A Hardcopy Terminal
| Field | Computing |
| Went Obsolete | 1995? |
| Made Obsolete By | Hardware flow control; xterms |
| Knowledge Assumed | Understanding of flow control |
| When useful | Many Unix terminals |
Old-fashioned serial terminals would send a Control-S signal when they couldn't keep up with the flow of data, and a Control-Q signal to restart the flow when they caught up. This was gradually replaced with the practice of using a separate wire for flow control, however the feature is still built into Unix and can be used to manually pause terminal output. In practice, however, modern terminals scroll so fast that pausing them by hand is not practical. This functionality now mostly serves to confuse newbies, which is why some vendors turn it off by default.
It does mean that the skill to be able to pause a very rapidly scrolling terminal window using CTRL+S remains - it just needs even more skill!
