In "The Sniper" by Liam O'Flaherty, what was the Republican sniper's first job?

We aren't directly told that the Republican sniper had a previous job, but we might make an educated guess that he was involved in some kind of academic discipline, possibly a student, and possibly with a medical focus.

The only direct characterization alluding to a prior occupation is in the introductory description of the sniper's appearance; he is said to have "the face of a student, thin and ascetic." This isn't necessarily evidence that he...

We aren't directly told that the Republican sniper had a previous job, but we might make an educated guess that he was involved in some kind of academic discipline, possibly a student, and possibly with a medical focus.

The only direct characterization alluding to a prior occupation is in the introductory description of the sniper's appearance; he is said to have "the face of a student, thin and ascetic." This isn't necessarily evidence that he was a student, per se. This may even be an analogy for the physical effects of his military service; a thin and ascetic face implies that one faces a strict way of living and is not prone to excess, which would fit the lifestyle of a soldier in an urban civil war. 

The second piece of evidence is the manner in which the sniper treats his wound after he is shot. He acknowledges the injury and the pain, and deals with it, but in a methodical manner; he goes through a series of motions to treat both the injury and the pain, almost as if he's done this before. We might imagine that he's either been shot previously, or that he has some experience with treating wounds of this nature, which would imply that he has some degree of medical training.