Gemara

(Mishnah): One may not write a loan document on Chol ha'Mo'ed. If the scribe has nothing to eat, it is permitted.

13a (Mishnah): We may not buy houses, slaves or animals unless they are needed for the Mo'ed or for the seller, if he has nothing to eat.

Question (Rava): Do we permit Sechar Pe'ulah (hiring a worker who has nothing to eat)?

Answer (Rav Nachman - Mishnah): ...Or for the need of the seller, if he has nothing to eat.

Suggestion: The extra words include hiring a worker who has nothing to eat!

Rejection (Rava): No, they merely explain what is considered 'for the need of the seller'.

Question (Abaye - Mishnah): One may not write a loan document on Chol ha'Mo'ed. If the scribe has nothing to eat, it is permitted.

This includes (permits) Sechar Pe'ulah!

Question (Mishnah - Chachamim): Three kinds of craftsmen may work on Erev Pesach until midday: tailors, barbers and launderers.

(Beraisa): Tailors are permitted because commoners may sew normally on Chol ha'Mo'ed (Erev Pesach is more lenient than Chol ha'Mo'ed). Barbers and launderers are permitted, for one who came from overseas or was freed from prison may take haircuts and launder on Chol ha'Mo'ed.

If we permit Sechar Pe'ulah, all professions are permitted on Erev Pesach, for they are permitted during the Mo'ed for a worker without food!

Counter-question #1 (Rav Papa): If so you should permit building on Erev Pesach, for on Chol ha'Mo'ed we may rebuild a wall about to fall!

Counter-question #2 (Ravina): If so you should permit scribes on Erev Pesach, for on Chol ha'Mo'ed they may write documents of Kidushin, divorce and receipts!

Answer (Rav Ashi): We cannot learn about Erev Pesach from Chol ha'Mo'ed. Chachamim forbade Melachos on Chol ha'Mo'ed due to exertion, and they did not forbid when it will cause a loss;

On Erev Pesach Chachamim permit only Melachos needed for the Mo'ed.

Rishonim

Rif: The question was about hiring a worker who has nothing to eat if the work is not needed for the Mo'ed. We conclude that it is permitted.

Nimukei Yosef (DH Gemara): The question was whether the Heter for one who lacks what to eat is only for Sechorah, or even for Melachah. Rav Nachman explained that 'if he has nothing to eat' is extra to permit hiring a worker who does not even have anything to sell, even if the employer does not the work for the Mo'ed. The Ramah says that a scribe may write a loan document for it is needed for the Mo'ed. He may not write anything not needed for the Mo'ed, even Sefer ha'Azarah (from which the Kohen Gadol reads on Yom Kipur). The Ramah's opinion is difficult, for the Gemara permits 'Sechar Pe'ulah' without distinction! Also, Amora'im suggested that all Melachos should be permitted on Erev Pesach. Melachah is not an exertion for one who has nothing to eat. Also, it is the ultimate Devar ha'Eved!

Rambam (Hilchos Yom Tov 7:24): If one lacks what to eat, he may do anything (normally) forbidden during the Mo'ed, including Sechorah, to earn what he needs. A rich person may hire him to do work (normally) forbidden on Chol ha'Mo'ed, to enable him to earn what he needs. One may buy things not needed for the Mo'ed if the seller does not have what to eat.

Rosh (1:23): The Yerushalmi permits selling only if one would not recover the principal afterwards, or if he does not have what to eat. The Yerushalmi permits even if he has what to eat, but he will spend more for Simchas Yom Tov and eat nicer food if he sells.

Poskim

Shulchan Aruch (539:4): One may sell merchandise during the Mo'ed if this will enable him to have more money and he will spend more for Simchas Yom Tov.

Beis Yosef (DH v'Im): The Rosh brings this Heter from the Yerushalmi. It is for one who skimps on Simchas Yom Tov lest he need to borrow from people later. The Rambam permits one who lacks what to eat, which connotes that he does not have enough, but perhaps it includes one who skimps.

Shulchan Aruch (ibid.): It seems that this is only for one who has limited money and he is reluctant to spend much for Simchas Yom Tov, but he would spend more if he had more money. It is not for one who could afford all his desires but did not plan to spend so much, and if he is permitted to sell he will spend more.

Taz (2): It seems that the Shulchan Aruch forbids only for an extremely wealthy person. Tosfos (Bava Metzi'a 70b DH Tashich) says that nowadays everything is considered necessary for our sustenance.

Kaf ha'Chayim (31): Some Poskim disagree with the Taz.

Shulchan Aruch (12): We may not buy houses, rocks, slaves or animals unless needed for the Mo'ed, or if the seller or the worker who will transport them has no food.

Mishnah Berurah (42): It is permitted also if the middleman (who receives some of the money) has nothing to eat. We permit sales for the sake of the middleman or transporter only if this is the real intent of the buyer and seller.

Shulchan Aruch (542:2): Any Melachah may be done by a worker who does not have what to eat, so he will earn and profit.

Magen Avraham (1): This connotes that he lacks even bread and water. The Nimukei Yosef allows someone with bread and water to write Tefilin. This implies that other Melachos are forbidden. The Heter for one who would otherwise skimp on Simchas Yom Tov (539:4) applies only to Sechorah, which is not proper Melachah.

Mishnah Berurah (7): The Magen Avraham says that if possible, he should do the work covertly, for not everyone knows that he has nothing to eat. If this is not possible, he may work openly. Others permit even if he has bread and water but lacks needs of Yom Tov.

Taz (2): 'Earn and profit' connotes that once he is permitted to work, he may receive more than needed for the Mo'ed. However, once he received enough for the Mo'ed from one (job), he may not do another.

Beis Yosef (DH u'Mah she'Chosav v'Chol): Most Poskim permit Melachah even not for the need of the Mo'ed for a worker without food, like the Nimukei Yosef.

Mishnah Berurah (6): The work may be done without a Shinuy.

Beis Yosef (DH Kosav): R. Yerucham permits only if the worker has nothing to sell. It seems that the Poskim disagree, for they did not mention this. It is unreasonable that the law was taught only for a totally bare worker. Also, it is unreasonable that Chachamim would forbid him to work and force him to sell Klei Tashmisho (Kelim he needs to use). We allow an Oni to take Leket, Shichchah and Pe'ah, without selling Klei Tashmisho! Perhaps even R. Yerucham does not require selling Klei Tashmisho; he excludes only one with merchandise to sell.

Kaf ha'Chayim (11): If he has Sechorah but cannot sell it for as much as he paid, this is Devar ha'Eved and he is permitted to work.

Kaf ha'Chayim (12): One may work to feed a wife and children that he is obligated to feed. Some forbid working to feed them if he is not obligated (e.g. children above six years); if they cannot work, they will beg. Others disagree, for one cannot fulfill the Mitzvah of Simchah when his children are begging.

Noda bi'Yehudah (1:OC 13): Shaving during the Mo'ed is forbidden due to Melachah. It would be permitted if it was a need of the Mo'ed, e.g. one who did not shave for a while, but Chachamim decreed against this lest people enter the Mo'ed unkempt. If one shaved on Erev Yom Tov it is forbidden only due to Melachah, hence a worker who has nothing to eat may shave others.

Kaf ha'Chayim (14): Many Acharonim forbid this.

Kaf ha'Chayim (16): One who is stringent about Chol ha'Mo'ed more than necessary will be rewarded with double what he sacrificed, like happened to Ravina (10b).